Labour leader Jeremy Corbyn is not known for his love of pomp and ceremony but embraced the white tie and tails look for a state banquet.
The politician is viewed as being uncomfortable with the more formal aspects of his role as Leader of the Opposition.
But he adopted the suggested dress code for his first sit-down Buckingham Palace dinner in honour of a president.
During the run up to the Labour leader elections, Mr Corbyn was spotted dressed down in a polo shirt, long dark shorts, black socks and trainers.
When he met the Chinese president Xi Jinping earlier, it was in a fawn jacket, white striped shirt and burgundy tie, but a few hours later he was in full banquet wear.
Before Mr Corbyn walked in to the Palace ballroom he would have met the Queen, who greets guests on their way in.
It was believed to be his first meeting with the monarch – but no cameras are allowed to film the receiving line.
He has yet to be formally inducted into the Privy Council when he is required to kneel and kiss the Queen's hand. He is planning to attend next month's meeting.
Mr Corbyn was seated between Wang Yajun, director general of the policy planning department of the Chinese foreign ministry, and the Lady Mayoress of London, Gilly Yarrow, the wife of the Lord Mayor.
The dress code, which is outlined on the invitations, is evening dress (white tie), decorations, full ceremonial evening dress for serving officers, or national dress.
It is intended as guidance, so guests are aware of what others will be wearing, and on occasion, some have worn black-tie instead. Mr Corbyn could have opted for this instead of white tie and tails but it would not have been the norm.
Following the president's speech, the national anthem was played by the orchestra and guests stood but, as is always tradition, did not sing.
Mr Corbyn, who did not join in with singing the national anthem at the Battle of Britain 75th anniversary commemorations, was spared having to test his vocal chords this time.