I don't know. There are some unusual things about your fork that match exactly the Belgian Sarolea:
1. the central fork spring that is wound small at the top, but remains larger at the bottom
2. the mounting holes immediately below the top for spindle
3. the frictions dampers with six-pointed star washers and butterfly thumbscrews
4. the mounting point in front of the lower fork spindle for the fixed damper plate
5. the brake anchor on the right side of the fork...
It could be something other than Sarolea - perhaps they bought the fork in from another manufacturer - but I'm way outside of my comfort zone talking about mid 1930s Belgian motorcycles! I don't recognise it as anything British, but I could be wrong.
Cheers
Leon
