Tax on uk private pensions

sorry if this has been covered before - but it is a very simple question and I feel sure someone knows the answer.

I am an early retiree resident and paying tax in France and have cashed in a couple of Uk private pensions. At first they were being paid untaxed but now I have received a new (UK) tax code saying that they will be taxed at source.

Can anyone please clarify if this is correct?