The first party to move loses the negotiation.

Who loses a property negotiation? Usually the side that shows first that it needs the deal more, and that rarely shows in the size of the offer.

Take a buyer who mentions, during a second viewing, that notice has already been given on the flat and the move has to happen by month end. It sounds like friendly conversation. But the agent works for the seller under the mandate, and that deadline will reach the seller sooner or later. When the offer arrives, the seller knows the buyer has very little room to walk away, and the counter offer is written with that in mind. Sellers give themselves away in the same manner when they cut the asking price before a single offer has come in, because buyers read the cut as pressure and bid lower still.

Moving first is a different thing from making the first offer. Somebody has to put a number on paper, and a well reasoned opening offer can be a strong one. The damage comes from moves driven by a deadline instead of by the property, because a deadline, once spoken, cannot be taken back.