Just as an update...
Ordered 2 Smart Sam +'s & a Land Cruiser (for t'other bike) from Winstanley's Bikes (ebay):
Email to say only 1 Sam in stock:
Email to say L'cruiser not in stock:
Deep breath, but ok send the one, which duly arrived & fitted to the rear wheel, which has Slime tube too (belt & braces).
The tire taken off has a thorn 3mm through it & slime has done its job, although made a mess between tyre & tube.
The new tyre has done about 300 miles & suits my riding surfaces zackly: I've had a couple of rapid stops - 1 on road & t'other on loose gravel & the rear stepped out of line in a most controlable manner: No histrionics whatever, so I'm very pleased with it so far.
Now waiting for its mate to arrive.