It is suggested, therefore, that once the employer or engineer does, in fact, read the bill of quantities as the breakdown of the bulk tender price and realises that there is a mistake which has been carried over into the tender price, the courts will rectify the mistake:

A contractor made errors in extension in a quantities contract, some in his favour, some against. The net result was an error of £1,881 in favour of the employers in the lump sum price.

Held: That the mistakes were so palpable that it was strange that the employers wished to take advantage of them, and the errors were rectified by inserting the correct extensions. 

And whatever the legal position, if the contractor is in the position that he must go on with the contract despite the mistake rather than pay damages, or where it is found during the progress of the works, in many cases he should not be held to the mistake. A contractor who is treated badly has openings for revenge in carrying out any major works, and usually only lawyers do well from the battle which results. There is also the point that if a bond is required the contractor may have difficulty in getting it if his tender is obviously too low, or if he gets a bond on a mistaken tender it may possibly be void (p.14).

On the other hand, of course, a contractor may make a judicious “mistake” in the hope of being given an opportunity to decide whether or not to correct it after the amounts of the other tenders have become known. If the engineer suspects that this has been done, he may advise the employer to give the contractor an opportunity of withdrawing or standing by his tender, but not of changing it. If the contractor stands by the mistake it is left in if it is in a rate; in other cases it is treated as an intentional deduction and the effect should be explained to and agreed with the contractor at the outset (see N. 6).