This is more than double the number who used the service in 2010, the Department for Work and Pensions (DWP) said.

The DWP has warned that auto-enrolment, which will require all employers to provide a workplace pension by 2018, could lead to 50 million dormant and lost pension pots by 2050.

The Pension Tracing Service helps individuals to find occupational and personal pensions that they have lost track of.

It uses a database containing information on more than 200,000 pension schemes.

Tom McPhail, head of pensions research at Hargreaves Lansdown, said: “On the one hand it is good news that so many people have been reunited with their dormant pension rights, however it is also unfortunate that so many people managed to lose track of so much money in the first place.”

Here, McPhail offers four top tips for making sure you don’t lose track of your pensions (and other investments):

• The fewer pension arrangements you have, the easier they are to keep track of. Whenever you change jobs, look at whether there is scope to consolidate your pensions, for example by transferring from your old employer’s scheme to your new one. Check any loss of benefits first.

• When you move house, make sure you notify all your pension and investment providers, and your employer, of your new address as soon as possible; ideally do this before the move is completed.

• If you are able to keep the majority of your pensions and investments on one platform, this will cut down significantly on the paperwork, reduce the risk of money being lost and potentially save costs as well.

• Make sure your spouse and dependents know where to find all the relevant information about your savings, investments and pensions. The best way to do this is with a simple asset register stored securely with your Will.