So did a few checks over the weekend, results so far.
Put the battery on charge overnight and it was reading 12.7 in the morning. Then disconnected the charger and left it standing a while and it was reading 12.4 by late afternoon, not sure if this is significant?
Also connecting the multimeter between the negative terminal and the cable shows 0.67mA so I take it there isn't a leak in the electrical system?
Checked it again the next day and everything is still fine, started the bike up and the voltage when idling was 14.24 but this dropped slightly to 13.94 at 3000rpm, again not sure if this is significant?
Anyway I bought a battery optimiser and connected that up yesterday and this morning the battery is reading 13.42V, so I think I'm going to turn that off now and just leave the bike standing for a few days and monitor the voltage
Bit confused about the location of the rectifier, as when stood on the left side of bike I can't see anything to the left of the battery, but there are a couple of items to the right but I don't think these are the rectifier, I've tried to insert a pic but I don't think it has worked!!.
Thanks for the help so far