To confirm; no restrictions on bootlace ferrules on 2.5mm^2 and 6mm^2 (or imperial equivalents)
With regards the comments on cables that got vapourised in the moderation, a brief history of the property is as follows:
Built 1950s (I think), back when the council didn't treat tenants with contempt and the tenants didn't treat the properties that they were given with contempt. (80 mm cavities, brick both leaves etc)
"Cooker" "sockets" and "lights" with a metal fusebox. Earths on the cooker and sockets. No earth on the lights. This was rewired in 1983, with an additional socket ring, an electric shower, all the lighting circuits replaced with T&E, and a split-load board with 30mA RCD for the sockets/shower. Again pretty good for the era, the workmanshpi wasn't at all bad, and had there been nothing else done to it I might well have left it alone. However...
Part P Pete the kitchen fitter came along, so now the end of the cooker radial is all dog-eared and jointed behind tiles.
Handy Andy the bodger came along, fitting downlighters in the living room, two-way lighting to the hall light, and an attic conversion. The lights downstairs flickered and made "bzzzzt" sounds if you jumped on the floor upstairs. (loose rose left under the floorboards as a JB) The two way switching was wired in such a way as you could turn the hall light on from downstairs, upstairs, or indeed both, but off required all switches to be off. The two lighting circuits were also linked in the process of fitting the two-way and the downlighters. Attic sockets fed off the upstairs lighting ring, obviously MCBed at dual 6A rather than single 6A due to the fudged wiring. Fugly metal light fittings with the earths not connected; ceiling pendants with the outer cores showing rather than the sheath
An SSIB certified mouth-breather fitted an alarm badly, and was probably the one to lose the blanks for the consumer unit/strips it's faceplate threads.
Then some Polish folks bought the house, and added double sockets by screwing/sticky-pad attaching them over the singles, with chocoboxes for live and neutral, but earth was too much trouble. Spurs off the ring by poking 1.5mm^2 T&E between the faceplate and the wall, then hanging 3 sockets off it.
Most faceplates or lightswitches were cracked in some shape or form, and many of the original ones had loose wires. (no ring continuity on N or E)
Bonding wasn't up to scratch (gas not bonded at all, water bonded >>>600mm from the entry point and in 6mm^2)
CU had missing blanking plates such that if you went for the main switch you'd probably get the live busbar instead, the shower was running off too small an MCB, and not all circuits had RCD protection.
All sounds nasty, but was fairly straightforward (untangling the lighting circuit excepted!) to bring "up to code" by changing all the faceplates and either extending the ring properly or removing the extensions, and swapping the CU for a 17th ed affair.
Cables were perfectly sound though; enough slack left in 1983 to do what needed to be done without replacing them, save for the cooker cable which gets a ruddy great JB and a new end on it, and some lighting cables that were easier to tear out and replace wholesale than terminate where they've been cut.
Perhaps this will bite me, and 30/50 year old PVC T&E will fail a hi-pot/megger test. I doubt it though to be honest; as I've never seen anything that "looks ok" not be ok. (though I have seen plenty that is obviously naff or nicked/gashed by another trade pass the megger even thought it failed a visual)