Finding colours to match those used 50 years ago is a bit of a minefield and you will find plenty of owners around who reckon they've got an exact match lets say taken from a good surviving section of paint found on the dummy tank under the rubber knee pad but in many cases they've just had paint mixed to suit so there is still no exact match code reference.
One example of this matching of original paint was done by a friend for the restoration of his Sport Arrow and was matched to Jaguar Coronet Gold, very nice Gold but to my eyes it was on the dark side, too rich in Gold.
Although I cannot be specific about paint codes I can point you in the directiion of R S Bike paints who appear to specialise in paint for old motorcycles and do cater for the Arrows and Leaders, although I've never used them you can always make contact and have a chat to them to ascertain how they decided on the Gold paint they sell for the Arrow. Tel 01707 273219. Go online and look at their website...
Another possibility is Redditch Shotblasting, tel Dave on 01527 529659 - I've had 3 dummy tanks and rear number plates painted by them in the last couple of years in Gold and they are doing a fourth dummy tank for me at the moment.
Comments by people who have seen the Gold on the bike at shows and events etc have been very impressed and at least say something like, thats the Gold they remember seeing on the bikes in the 60's.
It still might not be the exact Gold colour match but I'm very happy with it.
Hope this helps Ian, its the best I can do at the moment.
Hopefully we will hear from other owners with there Gold paint colours.
Good luck and please let us know any details of a Gold paint match.