The Goring directly confirms Catherine Middleton spent her final pre-wedding night in its Royal Suite, supported by an official Royal Family timetable and contemporaneous reporting.
Catherine Middleton stayed at The Goring in London on the night before her wedding to Prince William in April 2011. The hotel identifies the Royal Suite as her accommodation, while the Royal Family's official timetable and contemporaneous reporting place her at the property through the following morning.
Source conclusion:
The cited sources support a stay at the named hotel.
