The lack of a kitemark implies to me that this connector has been hoarded since before I was born.
It does have the standard number embossed on the plug, although it is worn and very difficult to read.
The actual standard is https://doi.org/10.3403/BS7666 . for reference. #TheRegister is pointing to some guidelines associated with the standard.
Alas, this seems to be #journalism by first search result. Although at least they put in more effort than the BBC did to try and fact check if this really was what the standard says.
The new draught excluder for the letterbox has just arrived. It is indeed a magflap, from the bloke in #Leicester who sells them from his dance studio just south of Victoria Park.
It fits, and clears the bolts. I just need my drill, screwdriver, spirit level, and some free time.
The delivery person didn't manage to get it through the hole in the door. (-:
It seems that one of those magflap thingies, which turn out to come from a bloke in #Leicester, are the only things that have enough of the right shape that they might be able to cover the entire hole in the door. I'd have to check how proud the bolts are, though.
It's amusing that the person behind them sells them from his dance studio just south of Victoria Park.
Ah, the joy of finding that there's a British Standard for letterbox sizes, that it has been around for 22 years, that all of the DIY shops nowadays sell door furniture that is in the size range specified by the standard ...
... and that the letterbox aperture in my front door pre-dates it by (ahem!) some years and is a completely different height:width ratio.
@law_sangeet_kaur If it's a BS ISO, then I have to wonder which national body actually did most of the grunt work. (-:
JdeBP