Star Wars fans may be forgiven for thinking Fiona Bruce lives on another planet.

After all, the Antiques Roadshow presenter dismissed one of the helmets from the iconic film as a worthless ‘bit of plastic’ – when in fact it is valued at almost £50,000.

Bruce, 50, displays her ignorance of the Star Wars phenomenon in tonight’s edition of Antiques Roadshow, from Chenies Manor, Buckinghamshire.

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Astonished: Presenter Fiona Bruce with collector Stephen Lane and the Star Wars helmet

The presenter is so taken aback by the helmet’s value she even conducts a straw poll of members of the public taking part in the filming, asking: ‘What do you think, £40-50,000 for this, surprising?’ She then adds: ‘I think to anyone who is not in your world it’s astonishing.’

The helmet featured in the first Star Wars film in 1977 and is owned by sci-fi collector Stephen Lane, who took it along for a valuation.

Bruce initially begins her interview by teasing him about his obsession with the movie blockbuster.

She says: ‘And are you by any chance a Star Wars super-geek? I am kind of getting that impression.’

Before 44-year-old Lane can answer the question, Bruce says: ‘Don’t even deny it. You were going to, weren’t you? Don’t bother.’

Bruce – who says she is a great fan of the original film – then tells him that although the helmet is difficult to value, the show’s experts believe it could be worth between £40,000 and £50,000.

She then expresses her own surprise at the valuation, referring to the helmet as ‘this bit of plastic’ – only to be corrected by Lane, who describes it as ‘this beautiful sculpt of plastic’.

First appearance: The helmet features in the original Star Wars film in 1977 which starred Harrison Ford, Carrie Fisher and Mark Hamill. The three will reprise their roles in a new film released next year

The artefact is known as a TIE pilot helmet, after the ‘twin ion engine’ craft piloted by the evil forces of the Empire, and is seen in the film’s climactic battle in which hero Luke Skywalker is locked in a dogfight before the Death Star is destroyed.

Just 14 were made for the original film and Lane bought his from a member of the crew who had kept it in his attic.

The Star Wars series of films is one of the most lucrative in the history of cinema.

A seventh instalment featuring original cast members Harrison Ford, Carrie Fisher and Mark Hamill is currently being filmed for release next year.

Antiques Roadshow is on BBC 1 tonight at 8pm.