The King has demonstrated his healthy living credentials by talking about fruit with a fresh juice seller during a visit to a south London market.

While marking the 750th anniversary of Croydon’s Surrey Street Market, Charles told a juice seller: “I really like pomegranate.”

Kevin Allagapen, who shared his wish to “make Croydon healthier”, gave the King a bottle of watermelon, pomegranate and beetroot juice.

Pomegranate is rich in antioxidants, vitamins and fibre and is known for supporting heart and brain health, improving blood circulation and reducing inflammation.

The 40-year-old market seller discussed his nutritionist background with Charles, who is known for his healthy diet and lifestyle.

Mr Allagapen, who has been running his Amati stall since August, told reporters he was “really stressed” about meeting the King but added: “It was good to meet him and he’s a nice guy.”

The visit took place ahead of the King’s 78th birthday on Saturday.

Charles stopped at a stall where he was presented with a large white cake featuring four Union jacks and a message reading: “Happy Birthday Your Majesty. 750 Years of Surrey Street Market, Croydon”.

The King said the cake was “brilliant” as he cut a generous slice while listening to children and students from Howard Primary School and Shirley High School Performing Arts College chant “happy birthday Your Majesty”.

Charles visited Asian convenience store Oreemart, co-founded by Amber-Rose Badrudin, a former candidate on the BBC’s The Apprentice.

Charles met with co-founder Michael Nguyen, who told him about their products including sweet boba tea to spicy ramen and dumplings.

The King joked with reporters in the shop by mistaking them for customers and asking: “Are you here shopping?”

Charles also stopped by Amanda Zhu’s market stand, which offers Chinese speciality Roujiamo, and Georges Whatle’s curry, meat and fish stall.

Mr Whatle told reporters it was the second time he had met the King, who told him his curry looked “lovely”.

Charles walked around the market with lead manager, Fiona Woodcock, at times slowed by the many people who had gathered to see him.

He also enjoyed music from London-founded, Indian-style band The Bollywood Brass Band.

Croydon-based South Asian dance company Beeja Dance performed and the arts organisation Global Grooves animated two giant carnival puppets called Padmini and Sivaji in the street.

Charles was given a fruit basket and birthday card by Croydon mayor Jason Perry.

Earlier on Friday, the King toured The Brit School in Croydon, where he watched a student fashion show, a rehearsal for a production of the musical Chess and a flash mob performance to a medley of songs released by the school’s alumni.