Why did the UK change from round pin to square pin plugs?

Na, it is classic behaviour really - bold assertion, (frequently with an unvoiced assumption or change of meaning that we are not privilege to), and then if challenged, gets the hump and wanders off with the ball :-)

he seems generally to have a short fuse when questioned

This could be particular pertinent in a discussion about 13A plugs :-)

one only need look at them

Are you a youngster? If not I find it very odd you've never tried stacking them & learnt the ways used to defeat that.

from my pov, life is too short. For all of us there are lots of things we aren't interested in spending a bunch of back & forth on. If that triggers your judgements, c'est la vie.

Ah. I've lived with round pin systems & stayed somewhere that was even older, BS3 something, no polarity or earth.

Old switchstart fluorescents would dim most of the way down if dimmed fairly quickly. Go slow & the filaments cool & they go out earlier. Also quick dimming hides a lot of issues from the unobservant. They could be dimmed all the way up & down at any speed with more complex control gear, all it needed to do was keep the filaments hot.

Carbon arc light are more troublesome than fluorescent.

On the contrary I've discussed many things at length. Just not interested in Rumm's occasional bouts of idiotic trolling or explaining things as basic as the alphabet.

BS372

I have met such adapters. I also routinely used adapters which could be stacked in the 1960s and early 1970s. There was nothing to stop me doing so. (Well, other than the tendency for them to fall out which could be countered by careful choice of the books used to support them.) And they would have been bought in high street stores such as Woolworth's. And you have not pointed to any reason why they could not have been sold. So another possibility seems to be that it is your experience which is lacking.

I figure if you have not grasped the alphabet by now, no amount of instruction, no matter how basic is going to help you.

However it is not all about you, others may welcome some explanation when you deem it not worthy of your time.

You know how to use a kill file if it bothers you too much.

snip

Fragile ego? Rarely found in here:-)

Not quite clear if this is the LED or the driver.

Changed the interior lights on the old car to plain LED with series resistor. Decided it would be nice to have them fade up and down. No problems getting a smooth fade out - but a problem getting a smooth fade up.

What is the circuitry for the fade? Usually it's easy to fade LEDs at low voltage DC as there isn't any SMPS to feed them.

Just a simple voltage ramp up/down. As I said, the fade out is perfect. Fade up, and it seems to need a higher voltage to trigger them than they'll run on when lit, as it were. Works perfectly on tungsten, though.

Not all woollies products were compliant.

Compliant with what?

legal requirements. They were in some ways like the pound shop of their day.

Yes I am aware of what Woolworths did/were :-)

I have not previously heard that there was a requirement that adaptors must prevent use in combination, so I am genuinely interested to know when this was the case, and how it was communicated and enforced.

i.e. In what statute are/were these legal requirements defined? Or do they stem from a British standard? If so which one?

Can you cite the legislation or BS doc to which you refer? I can see nothing in the current version of BS1363.

Hear, hear!

I only have the 1985 version of BS 1363 but that would have carried over whatever allegedly made my adapters unlawful in the 1970s .

The SI dealing with such things (The Plugs and Sockets etc. (Safety) Regulations 1994) applies (in addition to BS 1363) BS 5733 for adaptors (other than round-pin adaptors in BS 546). I have only the 2003 version of BS 5733 that but it too seems silent on the issue.

I just checked the 2014 version including amendment 1 - nothing obvious I could see there either.