Nightjar wrote
Frank Erskine wrote

Does anyone know of a supply of lead shot no more than, say, 3/32"
diameter pse?

Shotgun cartridges

Quite a few of those are lead free too now for the same reason as with
sinkers.

Sounds a little odd, but I want to fill old "sparklets" type bulbs with
lead to make weights for driving clocks.

A fishing tackle shop was suggested, but when I called at one I was
told that lead is banned for angling,...

The lead weights poisoned water fowl, hence The Control of Pollution
(Angler's Lead weights) Regulations 1986.

Solder would be a possibility, but a large proportion of it would be tin.

That depends which solder you buy. Eutectic lead tin solder will be 63%
tin and 37% lead, but EN ISO 9453:2006 Alloy No 123, such as Johnson
Matthey JM595, is 95% lead and 5% tin.

But you must be able to buy lead used for flashings etc.