This is a suit in equity brought to enforce compli*34anee with certain restrictions as to buildings imposed in 1850 in deeds of the several lots comprising a considerable tract in the south end of Boston as part of a general plan for their common benefit. The restrictions ás to the character and extent of building were in perpetuity and among other matters prohibited the erection of a building nearer than ten feet to the street line and over the rear of the lot. No question is made that the defendant* violated these two restrictions by the construction of a building commenced in March, 1906. There was evidence that the building was “ practically all up ” in the May following.
It is first contended that the bill cannot be maintained in this form by the present plaintiffs. The plaintiff Buttrick in his capacity as trustee was the owner of an estate within the protected area prior to July 28,1906, when he conveyed it to the plaintiff Stewart, who was a cestui que trust, taking back a mortgage to himself as trustee. There was evidence to the effect that this tranfer of title had been agreed upon a year before but was delayed on account of the appointment of a guardian ad litem. A mortgagee of real estate, even though out of possession, has such an interest as enables him to maintain an action for any part of the mortgaged estate wrongfully severed and converted into personalty. To this extent he is owner of the fee. Searle v. Sawyer, 127 Mass. 491. The reason for this is that the value of his security may be damaged. This reason extends to any act, whether done on the mortgaged premises or off, which may adversely affect the property described in his mortgage. He may maintain an action in the nature of waste or may go into equity to prevent the commission of waste. Restrictions like these create a right in the nature of an easement in favor of, as well as impose a liability upon, the grantee of every lot, growing out of the common character of the deeds. The interest is in a contractual stipulation for the common benefit. Evans v. Eoss, 194 Mass. 513. The nature of the right and obligation created by restrictions upon the use of real estate is such as to render their breach an injury to the fee of other land included within the scheme of improvement. A mortgagee is allowed to go into *35equity to prevent injuries threatened to the land covered by his mortgage, because any act in its nature capable of harming the value of his security may be such an injury as to entitle him to equitable relief and protection. Mortgagees are commonly permitted to bring suits in equity to nullify the orders of public boards or test the constitutionality of statutes, which in operation would impair their security. See for example Reagan v. Farmers’ Loan & Trust Co. 154 U. S. 362, 400; Reagan v. Mercantile Trust Co. 154 U. S. 418; Reagan v. Mercantile Trust Co. 154 U. S. 413. This principle includes the present case. There is no distinction in reason between sustaining a suit by a mortgagee to restrain waste threatened upon the mortgaged premises and one to prevent acts on other estates in derogation of legal rights established for the benefit of the property covered by the mortgage. See James v. Worcester, 141 Mass. 361; Everett v. Edwards, 149 Mass. 588; Rockwood v. Robinson, 159 Mass. 406, 408; Wilkinson v. Dunkley-Williams Co. 139 Mich. 621. The act of the defendant in violating the restrictions was a continuing wrong, and not one ended with the completion of his building.
No controversy arises between the two plaintiffs as mortgagor and mortgagee respectively. They both have an interest in the subject matter of the restrictions, which as to the defendant constitutes a unity, and they may properly join in one suit against him.
The single justice found that the plaintiffs had not been guilty of loches. This finding was based upon the hearing of oral evidence, and will not be disturbed unless plainly wrong. His memorandum states that neither plaintiff was aware of the defendant’s intention to violate the restrictions until his building was up. The finding is in accordance with the testimony of the plaintiffs, to which the single justice gave credence. It has been ingeniously argued that the circumstances of ownership of other property in the neighborhood and visits there, supplemented by the direct testimony of two witnesses to the contrary, shows that this finding is unsupported, at least as to the plaintiff Buttrick. But the testimony introduced by the defendant was not believed and the inferences from other facts were not inconsistent with ignorance by the plaintiffs of what the defendant was doing. In all this there was no error. The building was up about the mid-*36die of May. The suit was brought in the following March. This deferment is found to have been “ largely due to the interference of ” a mortgagee of the defendant’s lot, who was originally joined as a defendant in this suit, and “who finally dissuaded the counsel selected by them [the plaintiffs] from acting for them.”^/rhere is no hard and fast rule as to what constitutes loches. If there has been unreasonable delay in asserting claims or if, knowing his rights, a party does not seasonably avail himself of means at hand for their enforcement, but suffers his adversary to incur expense or enter into obligations or otherwise change his position, or in any way by inaction lulls suspicion of his demands to the harm of the other, or if there has been actual or passive acquiescence in the performance of the act complained of, then equity will ordinarily .refuse her aid for the establishment of an admitted right, especially if an injunction is asked. It would be contrary to equity and good conscience to enforce such rights when a defendant has been led to suppose by the word, silence or conduct of the plaintiff that there was no objection to his operations. Diligence is an essential prerequisite to equitable relief of this nature. Quiescence will be a bar when good faith requires vigilance. But so long as there is no knowledge of the wrong committed and no refusal to embrace opportunity to ascertain facts, there can be no loches. Upon the discovery of infringement of rights, such reasonable expedition is required in their prompt assertion as is consistent with due deliberation as to the proper means for relief.Won the other hand one, who —openly defies known rights, in me absence of anything to mislead him or to indicate assent or abandonment of intent to oppose on the part of others, is not in a position to urge as a bar failure to take the most instant conceivable resort to the courts. After the right has been invaded under circumstances, which would not defeat a plaintiff in seeking relief, and no substantial harm is shown to have accrued to the wrongdoer from delay, there is not the same imminent necessity for early enforcement of demands as exists before conditions have become fixed. Mere lapse of time, although an important, is not necessarily a decisive consideration.YxWithin the somewhat flexible limitations of these general rules, 'what may be loches in any case depends upon its peculiar facts.Linzee v. Mixer, 101 Mass. 512, 526. Cooke v. *37Barrett, 155 Mass. 413. Nudd v. Powers, 136 Mass. 273. Whitney v. Union Railway, 11 Gray, 359, 367. Haven v. Haven, 181 Mass. 573, 579. Tucker v. Fisk, 154 Mass. 574, 579. Hill v. Mayor of Boston, 193 Mass. 569, 574. Parker v. American Woolen Co. 195 Mass. 591, 603. Stewart v. Joyce, 201 Mass. 301. Daly v. Foss, 199 Mass. 104. An interval of perhaps ten weeks between the first knowledge by Buttrick and the' consultation with an attorney, during which he communicated with Stewart, who was out of the State, when there is nothing to indicate that it operated to the prejudice of the defendant, cannot be accounted loches respecting so important an infraction of rights as the present case reveals. The subsequent delay in instituting the suit is excused because it arose solely from the influence of one having a record interest in the defendant’s estate.
The defendant contends that the plaintiffs cannot prevail because they are themselves violating the same restriction which they seek to enforce against the defendant. The original deed from the city of Boston, through which the defendant gained title, contained the clause that “A dwelling house has been erected and completed on said lot in conformity with the conditions and restrictions.” The record shows that the single justice found that the constructions now upon the plaintiffs’ lot were those originally placed there, and that they were substantially the same on the two lots. It follows that they were regarded on all sides more than fifty years ago as a substantial compliance with the restrictions. The photographs and chalks of the buildings in the neighborhood furnish some indication of like buildings upon similar lots. Whether these constitute in small particulars technical deviations from a strict compliance with the letter of the restrictions is of no consequence after the lapse of half a century of general concurrence in a practically uniform construction of their meaning by acts done. Frost v. Jacobs, 204 Mass. 1. Jackson v. Stevenson, 156 Mass. 496. Moreover, the minor respects in which it is claimed that the plaintiffs have violated the restrictions are of a character wholly different from the infractions committed by the defendant, and therefore are not to be regarded as a barrier to the enforcement of their rights. Bacon v. Sandberg, 179 Mass. 396.
*38The single justice, after taking a view of the neighborhood affected by the restrictions, determined that there had been no change whatever in the character of the buildings contemplated by the scheme contained in the restrictions, with the exception of those at the corners of streets, and this was not of sufficient moment to interfere with it as a whole. This finding, supported by oral evidence as well as a view, was clearly warranted. ■ It leaves no room for the application of the rule of changed conditions laid down in Jackson v. Stevenson, 156 Mass. 496. In this respect the case is like Evans v. Foss, 194 Mass. 513.
It is strongly urged that a mandatory injunction ought'not to issue, for the reason that it would operate oppressively and inequitably, and impose on the defendant a loss disproportionate to the good it can accomplish, and that the plaintiffs ought to be relegated to financial compensation by way of damages. This remedy is a drastic one, and ought to be applied with caution, but in cases proper for its exercise, it ought not to be withheld merely for the reason that it will cause pecuniary loss. It has been found that the defendant with full knowledge of the restrictions “ deliberately attempted ” to override them, and thus to deprive the district of the character given it by the restrictions. He took his chances as to the effect of his conduct with eyes open to the results which might ensue. It has been the practice of courts to issue mandatory injunctions upon similar facts. Codman v. Bradley, 201 Mass. 361 and cases cited at 369. Curtis Manuf. Co. v. Spencer Wire Co. 203 Mass. 448. Downey v. Hood Sons, 203 Mass. 4, 12. Entrenchment behind considerable expenditures of money cannot shield premeditated efforts to evade or circumvent legal obligations from the salutary remedies of equity.
The costs allowed in the decree, including the expense of the surveyor’s plans, were within the discretion of the court, which does not appear to have, been wrongly exercised. R. L. c. 203, § 14. Stockbridge Iron Co. v. Cone Iron Works, 102 Mass. 80, 89.
Decree affirmed.
Throughout the opinion the defendant Finkelstone is called the defendant.