MGB 1 - £87.5K . I know numbers with 1 in them command silly prices but MGB 3 would probably buy you a new Evoque now if you still had it to sell.
I sold it in the mid 70's for £550 to a chap with a Bentley. That was quite a few pennies in those days.
Interestingly, when I enquired at the DVLA (or what ever it was called in those days!) MGB1 and MGB2 had never been released and mine was the first MGB reg!!
It cost me 4 guineas (£4.40) to make the transfer which was a real pain in those days as you had to own both cars and take the donor car to the main licensing office for them to inspect!