Yes,The Duke of York has closed as of the 21st March,The lease still had another 7 years on it.Howard de Walden the owner of the premises applied for planning permission through Westminster council last year to turn the the upstairs accomodation into 4 flats,but obviously as the lease was still running that was not possible.The managers left the Duke of York and within a week the pub had been closed and now i understand handed back to Howard de Walden,looks like the flats can now go ahead.
He has 2 other leased pubs in London,The Dover Castle and The Ordnance.