Terrorists should have learned their lesson by now - The UK doesn't give a toss about being bombed.
Firstly, terrorists are stupid - Everyone knows (or can Google) where the most strategic bombing locations are for maximum disruption and devastation, yet terrorists always hit some random place with comparatively little impact.
Heck, given where I live, you'd do far more damage to this country if you bombed my house than some semi-deserted street in Chelsea!
Secondly...
England has had the **** bombed out of it for decades by the IRA and other disgruntled parties. Thousands of bombs and bombings... but for the most part everyone just complains that their train/bus has been delayed, before phoning the wife to say they'll be late home for tea.
No-one in England is scared.
Scotland's people have a reputation for going up to burning terrorists and kicking them in.
Clearly no-one in Scotland is scared!!!
Wales has no targets of value apart from Eve Myles and Tom Jones.
No-one in Wales is scared.... apart from maybe Eve Myles and Tom Jones.
Ireland has nothing to do with Great Britain, but if they started getting hit I'm sure the retaliation would be far beyond anything the terrorists themselves thought possible, especially if GB wised up and took Ireland's side.
No-one in Ireland is scared.