I had a great stay at the Duchy house. A few things to note.
Location is amazing. It is very small, but if you're out an about all day and basically need a place to spend your nights, works perfectly. No complaints.
They are basically next to the Somerset House (a venue) so it's possible there could be concerts. When I was there on Friday and Saturday evenings there were concerts that were a bit loud if you had the window open (required in summer time as there is no A/C). However, these ended by 11 so not too bad. Just something to keep in mind.
Antony was super accommodating and let me leave my luggage before check-in.
Recommended!