ok, looking at http://www.salahtimes.com for prayer times, it gives a few different "Prayer Calculation Methods".
For fajr in Manchester, four of the five say 3:48am and one of them (um al qura) says 2:24am for the start time.
Seems like a massive difference in times. What gives? What is better to follow?
This is true, you have several calculation methods, depending on your country.
Here is a small explanation : http://www.mobilemuezzin.com/profile.html