Attacks are actually waaaay down in England. England was pretty crazy with IRA attacks in the 90's IIRC.
Yeah, in terms of pure numbers the post-2001 era has been tame for terrorism by UK standards.http://www.telegraph.co.uk/news/0/many-people-killed-terrorist-attacks-uk/
Those stats only take in to account fatalities too, the amount of injuries and property damage caused by IRA attacks positively dwarves anything done by Islamic terror on these shores.https://www.publications.parliament.uk/pa/cm199596/cmhansrd/vo960304/text/60304w13.htm
That list (scroll down) only goes up to 1996 too, they were carrying out attacks near enough a decade after that.
Of course the major difference is that - for the most part - the IRA didn't seek to inflict mass casualties, at least not amongst Joe Public. Where they attacked public targets they often (not always) phoned in warnings ahead of time to allow for evacuation of civilians. They still murdered plenty of innocent people, but their MO was very different to something like the 7/7 bombings or the Westminster bridge attack which were designed purely to inflict the maximum possible number of civilian casualties.
This is the first time since 2005 that a terrorist attack has succeeded in killing more than one person though so overall you'd have to say the security services are doing a fantastic job.