Cops in England don't carry guns, likely why it took 20 minutes.
There are many UK officers who carry lethal weapons. Many more do carry incapacitating devices like tasers. Keep in mind that most officers in the UK have repeatedly expressed a heavy majority opinion against carry guns.
This has not impaired the UK's paramilitaries in their occupied territories from carrying any range of lethal weapons. Lots of people in Ireland can attest to that.