No, there is no charge to either current pensioners or employees. There never has been and I see no reason why there should be!
The government took over all the assets and liabilities for our pensions up to 2012 and they have been paying over £5 million per year for the admin of that part – now known as the RMSPS.
But they have now put Capita in charge who are charging the government less per year. This link
gives you some info.