If you look at the BAA Gatwick website departure and arrival information it is impossible to believe that BA have anything than several delayed departures every day. The departure info is not specific as to the length of the delays but it does give an impresion of poor punctuality standards.
The last time I used them ex LGW there was only 1 desk open two hours before departure time in the early morning. . There were long queues. They obviously have severe staff shortages there.
In the last two years I have suffered delays of more than 4 hours out of LGW on them for flights that were scheduled as the first flights of the day on those aircraft. My last two inbound flights were also seriously delayed.
On top of all that are those foul all day deli meals. A really naff product. Generally not a good performance. On my preferred carrier the only time I have been delayed was when they waited for the passengers from a cancelled BA flight!
I think BA have got a lot of work to do to restore what was once a very good reputation at LGW.