Just another data point on the single rooms. My wife and I need to be in the area at the weekend and the Metropole is one of a few options in the area.
For the night I was looking at, a single room was half the price of a standard double. I gave the hotel in-house reservations team a quick call to see what their policy was with regards to spouse stays free. They confirmed it as not being guaranteed, but when they had availability they would happily upgrade and accomodate two guests at the single room price. They checked the night I was looking at and asked me to book it as normal and then let them know.
Booked the room and spoke to reservations yesterday and it was upgraded to 2 adults in an Executive Room without any fuss. All very good service, so ^ to them.