A “hidden masterpiece” by Anthony van Dyck has been discovered on the Antiques Roadshow after presenter Fiona Bruce said she had a hunch it might be genuine.

The “fake” Van Dyck was bought for £400 by a priest in Nottingham, but experts say the restored 17th century portrait could be worth around £400,000.

It was brought along to a recording of the programme in Newstead Abbey near Nottingham last year. Father Jamie MacLeod said he wanted to sell it and put the proceeds towards buying a new set of church bells.

Download the new Independent Premium app Sharing the full story, not just the headlines

The piece was spotted by the show’s host, Bruce, who said she had just finished making a show with art expert Philip Mould where she “spent weeks looking at nothing but Van Dyck paintings”.

After Mr Mould agreed it was worth taking a look at, and following months of restoration work to remove more recently-added layers of paint, it was verified as genuine by Van Dyck expert Dr Christopher Brown.

It is now the most valuable painting ever discovered on the Antiques Roadshow, which has been running for 36 years.

Fiona Bruce said: “It's everyone's dream to spot a hidden masterpiece, I'm thrilled that my hunch paid off, to discover a genuine Van Dyck is incredibly exciting. I'm so pleased for Father Jamie.”

Father Jamie, who runs a retreat house in the Peak District, said, “It's been an emotional experience and it's such great news. It's wonderful that new church bells hopefully will be pealing out to commemorate the centenary of the First World War in 2018.”

“Discoveries of this type are exceptionally rare”, said Mr Mould. “The painting's emergence from beneath layers of paint was dramatic. It's been revealed as a thrilling example of Van Dyck's skills of direct observation that made him so great a portrait painter.”

Van Dyck was the leading artist in the court of King Charles I, and a self-portrait recently sold to a private buyer for £12.5 million – sparking a campaign to save the painting for the nation.

The work discovered on the show is a portrait of a Magistrate of Brussels which is believed to have been painted as part of the artist's preparation for a 1634 work showing seven magistrates which was eventually destroyed in a French attack on Brussels in 1695.

The discovery will be shown on tonight's episode of Antiques Roadshow at 7pm on BBC One.