The fictional village post office in the series was blown up as part of a dramatic storyline.

She looked on as the windows were blasted out and cast members ran out to watch the aftermath.

The visit came during a day tour of Yorkshire, which also saw her take in performances by Spice Girl Mel B and opera star Lesley Garrett.

The Queen watches the post office explosion

The Emmerdale explosion scattered wood and debris across the main street and just yards from the royal visitor's feet.

Earlier the monarch had been taken to the village bed and breakfast and the Woolpack pub, where she met the stars of the ITV1 soap.

Mark Charnock, who plays Marlon Dingle in the popular soap, said: "She was cool as a cucumber when the explosion went off. The rest of us jumped out of our skins."

Paula Tilbrook, who plays Betty Eggleton, chatted to the Queen.

She said: "We know the Queen Mother used to watch but we didn't want to ask the Queen in case she didn't and it might have been a little bit embarrassing."

Guided tour

When the Queen arrived on the set, she was greeted by ITV officials and members of the cast.

She was then taken on a 40-minute guided tour of the village and chatted to members of the cast including retired gamekeeper Seth Armstrong, played by Stan Richards.

Emmerdale producer Tim Fee was on hand to escort the Queen through the village and explain some of the programme's history.

Royals and soaps

1982: Queen and Duke of Edinburgh visit Coronation Street studios 1984: Princess Margaret becomes the first royal to star on a radio programme when she appeared in The Archers 1999: Queen meets members of Channel 4 soap Brookside in Liverpool 2000: Prince Charles appears in Coronation Street during a visit to mark the soap's 40th anniversary 2001: Queen is shown round the Queen Vic when visiting the EastEnders set

Mr Fee explained how a set used to be a field but was transformed with some Yorkshire stone and erected from scratch in just 18 weeks.

After witnessing the pyrotechnics, the Queen made her way through the rest of the village and signed a visitors' book before leaving

The Queen is no stranger to soap sets, having visited EastEnders last year and Coronation Street in 1982.

Later on Thursday, she was entertained by a Festival Celebration featuring local choirs, bands and celebrities such as Mel B, opera singer Lesley Garrett and TV presenter Richard Whiteley.

She was joined by a 3,000-strong crowd to see stars that also included new Leeds United football manager Terry Venables and veteran sporting legends including Bob Appleyard, Brian Close, and Fred Trueman.

Her visit to West Yorkshire was also due to include meeting the public in Leeds' Millennium Square and welcoming the Commonwealth Games relay baton to the Temple Newsam estate, near the city.

A star-studded concert including Sheffield rock band Def Leppard is planned in the park to celebrate the Queen's visit.

The Duke of Edinburgh is also in the region, with activities including a trip to the National Coal Mining Museum, near Wakefield.