King Charles exchanged jokes with traders at Croydon’s Surrey Street Market as two anniversaries came together: its 750 years of trading and his approaching 78th birthday.

The monarch, who turns 78 on Saturday, shook hands with well-wishers during this week’s visit to the south London borough. Earlier, he had met students and watched performances at the BRIT School.

Among those greeting him at the market was Kevin Allagapen, 40, a juice seller and nutritionist who presented him with watermelon, pomegranate and beetroot juice. Allagapen has run his Amati stall since August, with a mission to “make Croydon healthier”.

He said he had been “really stressed” about meeting the King, but added: “It was good to meet him and he’s a nice guy.”

Charles was presented with a large white cake decorated with four Union jacks and the message: “Happy Birthday Your Majesty. 750 Years of Surrey Street Market, Croydon”. He called it “brilliant” and cut a generous slice as children and students from Howard Primary School and Shirley High School Performing Arts College chanted “happy birthday Your Majesty”.

The visit also showcased the market’s range of food businesses. At Asian convenience store Oreemart, co-founder Michael Nguyen introduced products including sweet boba tea, spicy ramen and dumplings. Fellow co-founder Amber-Rose Badrudin is a former candidate on the BBC’s The Apprentice.

The King stopped at Amanda Zhu’s stand, which sells the Chinese speciality Roujiamo, and Georges Whatle’s curry, meat and fish stall.

A local Bollywood band and dancers performed, as did Croydon-based South Asian company Beeja Dance. Arts organisation Global Grooves animated two giant carnival puppets, Padmini and Sivaji, in the street.

At the BRIT School earlier in the day, Charles watched a student fashion show, a rehearsal for the musical Chess and a flash mob performing to a medley of songs released by former pupils. The performing arts and technology state school’s alumni include Adele, Amy Winehouse and Raye.

The Mirror reported that police struggled to prevent the King being crushed as excited teenagers gathered around him. Charles laughed when one student called out “yes, boss!”