Finally, the three burners of choice for the boiler:

All customised from cooking stoves.
Left: Indian pressurised kerosene burner.
Centre: Pressurised alcohol burner hacked from kerosene pressurised camping stove with the nozzle drrilled out to 1 mm for alcohol.
Right: Gas burner from camping stove.
There is a locating ring fixed to the base of the boiler stand (screwed on from underside):

The ring is superfluous when using the kerosene burner as the burner is self-supporting:

The other two burners, however, drop neatly into the ring, which prevents them from moving away from the central position under the boiler and from toppling over due to drag on the fuel supply tube:


All three burners raise steam effectively, so it's mix and match.
I now consider the boiler to be finished, so – apart from a youtube video on the burners which I shall post in the near future – this thread is drawing to a close.
To everyone who generously offered their addvice (and in particular Duncan, who kindly offered to send me some bits and pieces) – my sincere thanks. Your help has been invaluable.
All the Best,
gary

Edited By gary arthur on 08/09/2019 22:18:41
Edited By gary arthur on 08/09/2019 22:20:03
Edited By gary arthur on 08/09/2019 22:22:55
Edited By gary arthur on 08/09/2019 22:25:38