Further update if anyone is still awake : tank has now been "gas" welded at a cost of £80. I currently have no other details nor do I know the extent of the damage to the existing paintwork -await collection via my fiend who is doing the work. Meanwhile bike is back with me -all it should need to put back on the road now is refinishing /repair / re-painting of the tank and swapping over the fuel lines / filter/ mountings and the cap etc. The OE tank cap is looking its age-like the owner-does anyone know if the replacements offered on Ebay are any good please?
https://www.ebay.co.uk/itm/334585475...3ABFBMqpSz8bdh