Yes - but if your bid is the only commission bid he has it should start with something like "I have £300 with me..." and then each time another bid comes in, online or in the room, he can take the next increment "with me" until your bid is passed. At any point that the others give up, that is the price you should get it for.
If he has two or more advance bids, then he starts at the first bid that clears the others.
If he starts at £2000 when yours is the only bid he has then he is breaking the law and risks losing his auctioneer's licence or worse. If he starts at £300, has no bidders online or in the room and starts taking non existing bids to try to bump the price up to your bid, he is also breaking the law - this is referred to as "taking bids off the wall". Some auction houses have bad reputations for either of these illegal practices and regular bidders avoid leaving bids with them.