edi local, I'd guess it's a reverse of a Dutch auction. Selling tulips they used to have a money clock which would start high and then start to reduce. When it got to your 'right price' you pressed your button and that pallet of flowers is yours. Hang on too long and someone else buys it.
I'm guessing that DRUK refers to that system in reverse which is, of course, more like a conventional auction except that the auctioneer states an increasing price until one of you caves in and accepts it
Haven't visited Auld Reekie for a while. In fact the last was for the opening of that weird Parliament building when we were permitted entry. Fortunately the beam didn't fall off that day