Given that the estimate was £10-12K, I imagine that the reserve was somewhat higher than £5.5K but, if so, why start so low ?
Is that a "come and get me" starting level ?
In the same sale, here's an example of a coin that didn't meet its reserve although it did have a bid, so I assume that no bids means no bids, to paraphrase Theresa May.
https://www.easyliveauction.com/catalogue/lot/d3cfc4b59ea829d9300d9c650f7b8836/0af8d24542e81eb9357e7ef448a6646f/timed-auction-of-750-lots-of-coins-medallions-and-silv-lot-454/