The statement in the press today, "British Airways slashes 10,300 flights" is pretty meaningless. It must have come from BA
PR department, because the media nowadays just cut/paste whatever the press release says, without editing (apart from silly superlatives like "slashes"), and they surely haven't added up a detailed list of cancellations. It also looks good for the media to have a big number, like 10,300, to stick in a headline, regardless of what it means.
But what is this number of flights ? Is it 1%, or 10%, or 50% of the previous flight schedule. And what percentage of currently booked pax are impacted ? I also suspect the old BA game of cancelling all the trunk domestics whenever there is any issue at Heathrow, while continuing to run the full daily schedule of half-filled JFK flights, may come into play as well.
One also wonders where the shortfall actually is. If a shortage of flight crews, qualified by type, it seems strange to cancel all the A320 flights while keeping all the 787 flights. If it's ATC, have the other Heathrow operators made just the same percentage reduction ? It it's immigration, how does consolidating pax from part-filled flights into full ones have any impact, as the same numbers will come through.