It's a good idea that buyer warns his card provider in advance due to the amount (£2,400). Card providers have procedures re "unusual activity" and spending a large sum with a new merchant (eBay) may count as that, and likewise if buyer's been on eBay for a while if the sum is far above normal. This should only delay things, but if that happens, a delay it does cause.
(Spoken from experience.) Card provider can also block payments if, as has happened to me, I buy a lot on eBay within a particular rather short period of time like umpteen in a morning (as many items were 'last one') - it was annoying when it happened, and the card provider refused to tell me their maximum nor the period of time. Had to wait a bit anxiously (a day, I think) before I could buy certain items I was about to buy but had been blocked. Let's hope your buyer doesn't go on a spree at the same time as buying from you.
