A number of points here I would comment on, as objectively as possible, interesting read with some interesting thoughts and opinions. Firstly, there is indeed a "watch list", 20 years ago it used to have around 4000 people on it, as of around last October, if my memory serves me correctly there was around 64,000 on it, I agree that today the police and counter terrorist services are woefully under resourced, so there are now 4, maybe even 5 tiers within that watch list, apparently we have the resources to only really "watch" in the truest sense of the word around 2000 I think, I don't comment just based on my past experience but of that I will explain no further.
As for the TA (now just simply called the regular reserve as they also comprise of ex regulars most of which have a reserve commitment until they are 55), apart from the fact that they have full time jobs and employers are only required to release them under certain circumstances and with very clear legislation (one example is the legal declaration of war, voted for in the UN etc), in many cases, Ops such as Afghanistan and Iraq sought volunteers to plug gaps because legally the TA could not be deployed without that declaration of war, there are some exemptions for certain specialisations. Thing is, even if they could the majority are not equipped for urban counter terrorism roles, pretty much all the real expertise we had in this field ended with peace in Northern Ireland, most TA unit's have specialist roles (Medical, Logistics, Communications, Engineers), this enables them to have just 10% of the training time of the Regular Army but still have highly skilled reserve Forces, it's just in narrow fields of expertise if you get my drift. Of course you also have TA Infantry, some of these units are "role specific", so a few may have a "Home defence" role but in general terms they are in some cases "Jack's of all trades", there is a very good reason why law enforcement has specialist anti terrorist units and the Armed forces have the SAS, SBS etc and that's because that's all they do, day in and day out, train, train, then train again to make them the very best, sadly gone are the days where a regular Infantry battalion would move to Catterick Garrison having spent 5 years in Cyprus in a peacekeeping role to then spend 5 years in a Northern Ireland reinforcement role.
So, we find ourselves in 2017, with a police force roughly half the size it was 30 years ago, with an Armed Forces roughly half the size it was 30 years ago and with budgets to match (when I joined there was still a cold war, the British Army had 7 operational warfighting divisions), 4 of which were permanently located in Germany, we now have only 1 truly deployable Division and what......... we wonder why, when the threat during those 30 years has increased 10 fold, despite the end of the cold war and peace in NI that we struggle to cope? Answer? (just to divide opinion), when we have significant terrorist threats, don't let them fester for 10 or 15 years paying lip service to trying to minimise the impact and holding hands with those that either encourage or harbour them, go in there and eradicate the problem with massive force and viable intelligence from the get go, you can't cock about with these people, give them half a chance and they will take your loved ones away from you.............. I stress, I am not including the likes of the Iraq invasion in this which was a different scenario and one that I on a personal level did not support.
Apologies for rant, at best if you read this you may sleep well tonight