I don’t live in Nottingham, but my folks do and two of my R’s are garaged up there at the moment. Will be up there again next week.
Re. starting unevenly- is this only after the bike has had a long layup or do you find this more regularly?. A while ago when I lived in Australia
my UK bikes were garaged up for most of the year and only run in summer. I often found they would only start on one or two before eventually firing up on all four. The solution seemed to be to replace new plugs each year. Once the plugs have been fouled with petrol they seem to be near useless.
Re. Exhaust.. is that a rusted out original system you have there by chance ?