Jo Crowley MADRID/LONDON (Reuters) -Santander's plan to buy TSB for 2.65 billion pounds ($3.61 billion) and boost its position in the UK came together only a few weeks ago, after the Spanish bank had been considering a possible exit from Britain,

The purchase will create a lender with nearly 28 million customers and the third-largest number of personal account balances in the UK.

TSB customers could also be moved over to Santander, which would become the third biggest UK bank. Santander said it "intends to integrate TSB in the Santander UK group".