What have you tried? Here are some hints in case you have problems getting started:

1. If you have the epoch (seconds since 01-01-1970) at hand, add 3600 seconds and render output again.
2. If not, convert your date into an epoch and proceed with previous step.
3. Regexp might work. Hints: perlre ('e' switch); sprintf
4. Have a look at CPAN modules. Maybe Date::Manip or Date::Time is something for you?

What's wrong with the advice given in How to get current UK time?

HTH