Great question — answering as the UphillTech team:
Ordinarily, BA flight numbers give some clues as to the route being flown; for instance, I think all flights to the US have an odd flight number and those headed back to the UK an adjacent even one. In particular, there are various assigned flight number ranges to distinguish things like codeshares, charters and the various London hubs. In the context of this question, flight numbers BA2530 to BA2899 normally denote LGW short haul operations. However, during the pandemic BA stopped all such operations at Gatwick apart from some domestic feeders. Some flights were cancelled outright; others were moved to LHR. It was convenient at the time to keep the flight numbers the same, for a variety of...
Full answer by Gray Taylor: https://travel.stackexchange.com/a/169883 (CC BY-SA 4.0).
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