Section 44 was pretty much abolished some years ago. I think it was originally a terrorist stop and search act that was systematically abused by the boys and girls in blue. After nearly ten years it had reportedly caught a memorable number of terrorists. Zero.Although current rights are admittedly somewhat different to the Ways and Means Acts used of old, is is not strictly true that an individual can only be searched if they present immediate suspicion to a specific police officer.
Sec60 for example is a stop and search power that allows indiscriminate searches and can be invoked by a senior officer if there is belief that a certain area is susceptible to violent acts. Nearby to a football stadium for example.
Sec44 is another indiscriminate search power which comes under the terrorism act and can be invoked, as you would expect, to any area susceptible to terrorism. Your search at a London tube station maybe? I would suggest that you did the right thing to acquiesce at the time...
Of note (depending on when your tube search was) is that when Sec44 was first introduced a blanket footprint of the entire Greater London area was authorised for 10 years so being near stations/high areas of violence didn't even come into it. Although the ability to invoke such a broad area was repealed in 2012, the act is still live but now generally applies to designated, smaller areas.
I guess my point is that a Sec44 or 60 could be authorised in any area at any time and it is entirely likely that a member of the public will not have a clue it is in place. Just something to be aware of if you are adamant that you are carrying your locking blade because it provides you with something 'handy' which a folding one won't.
I fully appreciate your view regarding being sensitive about your rights, but I for one am extremely glad that both the above policies exist.
It had however been considered a human rights abuse by the European court and was deemed to be be illegal. The Uk government had no choice but to repeal the law although I seem to remember Theresa May trying to take some credit for getting rid of it.
60 is different though as like you suggested it has to be within an area that is designated by a senior office. I am not under the impression the senior officer could just say "London" and that would be the area.
Apparently the chances of stop and search under both acts if you were black or asian was seven fold. Section 60 is apparently little used these days due to the abuse of the act by the boys and girls in blue.