@ BH. You have never seen a Belling Lee plug like THIS
I don't believe you.
What are you talking about? I've never seen a standard UHF TV aerial plug (if that's what you are calling a Belling Lee) that has a hole in the end of the centre conductor - by which I assumed you meant a radial hole not a concentric one. Even the screw type have a concentric hole, necessary for inserting the core conductor of the cable!
How would you solder one like that? Any residue on the outside of the pin interferes with the mechanical fit in the socket, and risks melting the plastic insulator. I expected a solder bucket at the inboard end of the pin, and a thermally resistant insulator. How do you know these are supposed to be soldered - where does it say so?
OK, I found this, which gives instructions - but that is not a spec sheet, just somebody's advice:
...in which it says
"Unfortunately the plastic holding the pin is made of a low-melting point plastic. Touch the soldering iron to the protruding centre of the cable and not the pin - the solder will wick up into the pin as it melts but you get a few seconds more before the plastic melts"
...which says to me it is not manufactured with soldering in mind. I have never
soldered an aerial lead, I would rather leave the screws unfitted (if it has them), and I have never suffered from:
"If you absolutely insist you can't solder the inner conductor, then at least bend it about 10 degrees 0.5 cm from the end so it makes contact with the pin when the plug is freshly made. That will last you about 6 months to two years of acceptable contact in practice. If you don't bend it all bets are off - you are about to make a scratchy, intermittent connection whatever you do."
Utter balls. Perfect contact is not necessary, unless you require a DC path for powering an aerial amp. I do kink the core, but that's only because the core on a modern cable is too thin to be a snug fit in the concentric hole. I have also folded the core and pinched it to fit.
The article also says
"DTT demands the right way"
(the "right way" being soldered of course)
As far as I know, DTT imposes no greater demand on the quality of the connection than analogue did, unless you are in a marginal reception area (or have a poor aerial) and need every last dB to get up the cliff edge (which for analogue would be graceful degradation).
OK, I'm not saying you shouldn't
solder, only that before this discussion I hadn't heard of it. I maintain that the plugs are not designed
to be soldered, and doing so is a bodge. Note that the cable end shown in Trev's link is not
soldered in the manner described. I would prefer to crimp than solder, because soldered leads are more brittle.