Queen interrupts BBC's 24-hour news coverage and then talks about the mud at Glastonbury

The Queen stole the show when she surprised two BBC presenters live on air today during a tour of the corporation’s state-of-the-art new broadcasting centre in London.

There were huge laughs when Julian Worricker and Sophie Long, who were going out live on the BBC news channel, turned to see her watching them. She had approached the enclosed studio but the two presenters inside did not realise she had reached their floor.

After finding they had a special audience, the pair acknowledged her presence with a nod before continuing the broadcast. The light-hearted moment came as the monarch officially opened the new HQ in central London.

The Queen also joined a broadcast on Radio 4 and visited Radio 1 during the tour of revamped Broadcasting House.

In the short address broadcast live by the BBC and around the globe via the World Service, she referred to a previous visit to Broadcasting House with Prince Philip shortly before her coronation 60 years ago.

She said: “I was struck then, as I am now, by the sheer pace of change which has transformed your industry over the past 60 years — years during which broadcasting has enriched our lives in so many ways.” She it was a “great pleasure” to declare the HQ open.

Crowds gathered outside the building, which was flying the Royal Standard, cheered her as she arrived.

BBC Trust chairman Lord Patten and BBC director general Lord Hall escorted the Queen, wearing a powder blue coat and hat, on the visit.

She began the tour by visiting Radio 1 and meeting hosts including Nick Grimshaw, Trevor Nelson and Sara Cox, and seemed in good spirits as she chatted happily to executives.

She then visited the station’s well-known Live Lounge to watch a performance by The Script. At the end she chatted briefly to lead singer Danny O’Donoghue, a judge on BBC1 show The Voice.