This detail is from the porte cochere at the front of Hove railway station. It's on the London to Brighton line, but there's an even stronger London connection than that. The porte cochere itself, a large covered expanse providing shelter for those arriving at the station and their vehicles, was originally part of Victoria Station. It was moved to its present location when rebuilding at Victoria made it redundant there.
The tiled initials are 'LBSCR'. They stand for London Brighton & South Coast Railway, a company formed in 1846 when the original operators, the London & Brighton Railway, amalgamated with several other companies. They continued to own the line until they merged once again, forming the Southern Railway in 1923. The LBSCR was also known as 'the Brighton Line', a name which lives on in bingo calls ("five and nine...").