I emailed the seller again just to see if he could shed anymore light on the bike. This is what he came back with.
The chroming was already on the bike, so when I had it re-enamelled I asked the guy doing it to make sure the chrome was intact!
The 753 decal was replaced when the frame was re-enamelled. The original colour of the frame was white, although it was not 'pearl white', more of a chalk white colour.
It could well have been Knight, but I can't be certain. The bike itself seemed to be fairly 'known' about in local club circles when I bought it, and certainly when I did the one and only Bungay Town Race on it ( I think that was 1991), the guy checking over the machine actually recognised it!
I hope to see Paul @ Life Cycles Saturday to see if he can shed anymore light on the bike.