Wow! Eventually found a gap in the 'need the puter' all the time and ran the 7 repair. It ran 'Start up Repair' and did nothing. Bootrec.exe likewise. Wrestled that lot to the ground. Eventually, losing hair, I deleted all bcd entries , but can only boot into 7.........It appears that 7 then needed to load 'drivers' for my new drive (500 replacing 2x160) and after it did that it kindly changed ALL my drive numbers and letters and inserted a new partition (unlettered) on the 500gb drive which 'turned out' to actually be the C partition, making the third partition D! I spent a while resetting drive letters.
Eventually with easybcd I got back to the land of the living. Not an experience I would willingly repeat!