* Banks lower on Mervyn King's comments on regulation

* Energy firms, miners down

* Food retailers up; Nomura hikes Tesco target

* London Stock Exchange falls on Goldman downgrade

By Paul Sandle

LONDON, Oct 21 (Reuters) - Britain's top share index was 1 percent lower in midday trade on Wednesday, as miners and energy stocks fell on weakness in commodity prices while banks fell after the BoE Governor said regulation would be tightened.

At 1208 GMT the FTSE 100 .FTSE was down 57.92 points at 5,185.48, after closing 0.7 percent lower in the previous session having hit a fresh high for the year at 5,298.54.

Banks weighed on the index after King said late on Tuesday a fundamental rethink of how the banking sector is structured was needed to prevent a recurrence of the financial crisis. [ID:nLAG003852]