We had a very nice time at Steve's flat. Steve was very welcoming and flexible about timings and kept my bag on the last day.
The surroundings of the flat are very nice, especially Marchmont street (cafés, libraries, shops) and the proximity to St Pancras is extremly practical.
The only negative thing was the bulding site in front of the house that began at 8am but we weren't planning on sleeping late anyway so it was not a problem for us.
Overall, a really warm recommandation for this flat!