case Berwick and turner against GYBSON in the exchequer Chamber a declaration  on a covenant to procure the reversion of a office provide the plaintiff will  give security for the rend allege he be always ready to give the security be  sufficient in a action on a proviso to do a certain act it lie on the  defendant to show nonperformance in a action on a covenant to procure the  deputation to a office in the same manner as another be depute the defendant  be estopped to say there be no deputation and the manner of the former  deputation need not be show if breach of covenant be sufficient allege it need  not conclude et such non to hold c covenant for that the defendant covenant by  indenture with they whereas the king have grant the office of aulnageor of all  drapery to the duke of Lenox who have make the plaintiff his deputy for seven  year through all place within the county of Essex except Colchester that the  defendant covenant with they whereas the say duke have make a deputation of  that office in Colchester for two year to one Everden that at the end of the  two year he will procure to they a deputation for seven year in the same  manner as Everden have it proviso that they upon the make thereof shall give  security for the payment of one hundred pound per annum rend for it and  performance of covenant and the allege in facto that they be always ready to  give security for the rend and that the defendant have not procure the  deputation the defendant thereupon demurrer after argument the declaration be  adjudge good and upon a writ of enquiry of damage damage be assess to five  hundred pound judgement be give accord a writ of error be thereupon bring in  the exchequer Chamber the first error assign be because they do not allege  performance of the promise but only a readiness to have give security say non  allocatur for they need not give security until deputation make and the  nonperformance of the promise ought to come on the other part second because  it be not show that they require a deputation to be make and the quality how  the other be make nor in fact that there be any deputation make to Everden say  non croak throw allocatur for the covenant mention that there be a deputation  and he be estopped to say the contrary and at his peril ought to procure such  a one to the plaintiff as the other be and it lie not in their notice how and  in what manner the other be and that the defendant ought to procure it immedi  croak James er p ately after two year expire that the plaintiff may not lose  the profit thereof after they be due three because they show not the breach  accord to the usual form et such non to hold assembly in hoc c say non  allocatur for there be a breach thereof sufficient allege they need not make a  repetition and when the substance be allege the pursue of the usual course be  not material wherefore the judgement be affirm croak throw easter term James  in the king bench sir Thomas Fleming Knt chief justice sir Christopher  Yelverton Knt sir David William Knt sir John croak Knt justice sir Henry  Hobart Knt attorney general sir Francis Bacon Knt solicitor general