It's a Blockley Superior Tube 400-19...
The Coker line sold by Summit Racing in the States looks ok as well. This tube is spec'd out for 4.00/4.50 and will fit 18/19 wheels.
Part number for the Coker is COK-86275
The markings on the tube state that the tire is made in the EEC
The Coker Excelsior tire is made in Taiwan but looks superior to the Blockley and is a dead ringer for it.
Thanks. That's a big help and seems more in line with a reasonable price.