Below you’ll find a host of time conversion tools. They’ll convert your 25m times to 50m times and vice-versa. They’ll also convert from yards to metres and vice-versa. Very useful.
SportSys: http://www2.sportsys.co.uk/time.asp
City of Leeds: https://swimleeds.myswimmingclub.uk/v1/time-converter
The WASPS Story can be found on ‘Statement and Blog Update’ page.