A maharaja, Colonel Nawab Sir Umar HayatKhan, lived in India (actually in the area which is today's Pakistan), which was owned by Britain at the time....this is in 1929.

He had a servant, Mir Malik Sultan Khan. He was an Indian chess master. In India, the rules were slightly different. The pawn could only ever move 1 square. There were some different rules for castling - but I'm not sure what they were- and if a pawn reach it's "queening square" it could only become the piece whose file it was in the original position (e.g. if the pawn reached b8, it became a knight, if c8, a bishop..)

This maharaja brought Sultan Khan to England with him. In a very short time Khan learned the Western rules. The maharaja was a friend of King George V and had some influence. He entered Sultan Khan in the British Open.

Khan won.

He played first board for England during the World Chess Olympiads at Prague 1931 and again at Folkestone 1933.  He continued to play chess for 4 years. He never finished less than fourth in any tournament. He beat Capablanca, Rubinstein, Tartakower  in games and drew against Alekhine. Oddly, he always lost to William Winter. Winter finished low in almost every tournament, but always beat Khan .

He was a servant, some think a slave... One time his master gave a diner party and invited many great chess masters. Rueben Fine was there and relates how Sultan Khan was used to serve the food and drinks. He said it was very uncomfortable since he felt it was the others who should have been waiting on Khan.

Sultan Khan was somewhat unattractive in appearance. He was short and rail-thin. He always had a cold due to the British climate which gave him a perpetual runny nose. He was also illiterate and couldn't keep his own scorecard. He  had no book knowledge of chess theory. He was said to be a capable blindfold player.

He was taken back to India in 1933 by his master, never to be seen by the world of chess again. It's not certain what happened to him. One source says he became a farmer and died in 1966, but it's not confirmed.