i think i know this one!
(i have friends who work in the construction industry, and they communicate, inter-company, via some kind of hive-mind)
the initial estimate/tender said £Xmillion (?)
when it came time to start signing contracts, the construction company said 'did we say £Xmillion? - we've had another look at it, and now it's X+50% - we assume that won't be a problem?'
so SCC told them that yes, it was going to be a problem, so it had to be re-scoped, and put back out to tender...
it seems to me that's exactly how we want SCC to behave when a contractor plays that kind of game....
(low-ball the tender, then ramp it up just before closing the contract, in the hope that the impending deadlines help force the issue)