Stayed in Unit 3 23-26 June when temperatures in London were 24-29 °C, and the room was insufferably warm. There is a large fan, which goes some way to help, but the large windows start receiving the heat of the sun from dawn, and this heat is ‘baked in’ to the room for the rest of the day/night. The two large windows are the best part of 1.5 m tall, but only open to around 10 cm (presumably for safety/security reasons), and even then, I had to prop them open with the coffee mugs provided to keep them open.
Location-wise for Westminster and Piccadilly etc., it is actually really handy, if a little noisy from the pub below.
I’d consider returning, but not in the summer months - unless the temperature is guarantee to be below 20 °C at the very maximum!