A group of German exchange students have been discovering a medieval link between their home town and Norfolk at Norwich castle museum.

Twenty-seven students from the Albert-Schweitzer-Realschule in Mayen are being hosted by North Walsham High School this week on an exchange.

It's a return visit for the students who last October hosted pupils from North Walsham in Mayen. On that trip the English students visited the mines around Mayen.

And on Saturday the German students were able to handle a millstone, made from volcanic rock quarried in Mayen, which had been exported to Norfolk during the medieval period.

The millstone, which was used to grind corn, was discovered at Ingham churchyard in the 1960s, and is now at the Castle museum, where it is normally kept in storage.

The students also got to handle some of the museum's collection of Anglo-Saxon artefacts including brooches and pottery.

Martin Koch, who teaches English at the school in Mayen, said: 'The children are all getting something out of the exchange. 'Since the visit last year, a lot of them have stayed in touch. They are also learning about the strong links between Germany and England in medieval times, and that everything is connected. And that the English students have the same ideas and problems that they have.'

Simon Weal, language teacher at Norwich Walsham High School, said: 'The only difference between the children is the language.'

The students were welcomed to the museum by Jan Bensley, who said: 'The millstone was imported into Norfolk during the medieval period, and would have probably come through either Great Yarmouth or King's Lynn.'

Student Zoe Trevatt, 16, from Mundesley, said: 'Going to Germany last October was a good experience. We get on well together.'

Svenja Herrmann, 15, said the English students were very friendly, and Björn Ternes, 15, added that he enjoyed meeting new people, and discovering a new culture. 'It also helps me to improve my English,' he said.

This is the 43rd year the two schools have operated an exchange scheme. Mayen is a town of just under 19,000 people, near Koblenz.