Apologies for the delay in writing this.
My partner and I were in the All Inn One on Friday evening and having checked our phone records we left there just before 7pm.
The point is that around 6:30 we spotted a red flashing light in the vicinity of the bike rack. In the poor light we thought we could see two people - but not clearly enough to identify them. Did your bike have a flashing alarm ?
Having worked on the railway and managed CCTV installations on stations, I am afraid that approaching the operating company will not bring the result you would hope for. Most have a policy that is intended to prevent provision of extracts of recordings to the public.
However do try approaching British Transport Police - technically they may accept that the crime has happened on their patch. If they do - they have the technical capability to extract the necessary records from the operating company’s footage.
The technical spec for on station CCTV is to provide prosecutable quality imagery even in low and zero light conditions.
Oh and the twenty minute thing is absolute nonsense. A scan of the video stream at high speed will enable an operator to look at several hours of coverage in minutes and allow them to narrow down to when the theft occurred.