* FTSE 100 falls 1.3 percent to a one-month closing low

* Banks weigh after shake-up at RBS, Lloyds; UBS results

* Miners fall on demand fears

By Tricia Wright

LONDON, Nov 3 (Reuters) - Britain's top share index fell to its lowest closing level in a month on Tuesday, led down by banks after shake-ups at Royal Bank of Scotland (RBS.L: Quote, Profile, Research) and Lloyds (LLOY.L: Quote, Profile, Research) and poor results from Swiss peer UBS (UBSN.VX: Quote, Profile, Research).

The FTSE 100 index .FTSE closed 67.29 points or 1.3 percent weaker at 5,037.21, having surrendered the 5,000 level for the first time since Oct. 2 earlier in the session. It traded as low as 4,985.09.

Upbeat data from across the Atlantic helped the index pare its losses, with new orders received by U.S. factories beating Wall Street expectations and rising 0.9 percent in September.

"There's always going to be a bit of profit taking on any sustained move higher and that's certainly what's happening today," said Angus Campbell, head of sales at Capital Spreads.