Bike I.D please (not sure if its even a FB)

Hi Guys,
I brought this bike a year or so ago but put it to the back of the shed when the merlin came along. i was told when i brought it it was a Francis barnett Trials but i have been unable to ID it. There doesn't seem to be a frame number on the steering head like the merlin but i have discovered a number on a little plate on the frame near the front of the petrol tank. (DS830) but i suspect that isn't a frame number. Any idea's to ID it would be useful or if its just a trials modified road bike (kestrel or something as thats the closest fb frame i have been able to find visually) Ive uploaded 2 photo's one as i brought it and another that shows the frame in a little more detail. (image removed to save space)


Like i said..any ideas would be useful
Thanks
Kim

[(removed to save space)
heres the frame photo

Thanks
Kim

Thanks JH, I suspected it may be an excelcsior as i have another bike waiting its turn and ID'ed that as an excelsior a while ago. It has the same frame as this one but i was thinking maybe they shared frame manufacturer's (still learning)

The only frame number i can find is the one stated above ( DS 830) the engine that is/was in it is a 10D (938/20247D).

Thanks
Kim