Nigel Dean frame number identification

[MiffwS17]

I have just bought what is thought to be a 1979 Nigel Dean bike with 531 tubing. The bottom bracket is stamped simply with the number 2. It would be great if anyone knew what this may mean as it is unusual to have so few numbers? Any input would be great!

 

[Robbied196]

Nicely built quality frames I know Nigel Dean had a shop in St Albans but think his frames were made up near Hull. I've had a couple myself including a Tour Master, I don't remember either having frame numbers.

I think I read after packing up building he went to team management.