Help identifying my bike frame

[thegeorgeuk]

any help appreciated.

it has a cast cinelli bottom bracket
020289 stamped on bottom bracket

 

[sunympholepsy]

It closely resembles George Longstaff’s work but I guess it would’ve had ‘GL’ prefix in the serial number (or ‘RS’ from when he built for Swinnerton). However, I am by no means an expert.
Whatever it is, it’s certainly nicely built.