WARNING: This article contains spoilers from Antiques Roadshow.

An guest admitted he was wrong after initially doubting the provenance of a guest's valuable painting.

Expert Rupert Maas encountered a guest at Belmont House, Faversham, during the BBC daytime show who brought along a painting that sparked quite the stir among those present.

Maas remarked: "You're sitting there all day and people bring pictures and the thing they want to know is it or isn't it by the artist that it says it's by.

"In this case, your picture says it's by David Hockney. This is not at all what I'm used to seeing by David Hockney.

"David Hockney is one of Britain's leading modern painters so you'll have to tell me what your case is", he challenged the guest.

The owner of the artwork recounted: "My grandfather saw two young artists on the platform when he was signalman in a tiny station called Trimley St Mary between Felixstowe and Ipswich.

"He noticed their equipment and invited them into the signal box and gave them a cup of tea.

"He eventually invited them home for Sunday lunch because they were living in straightened circumstances.

"So they came for Sunday lunch and he said 'Oh bring a painting' and Wallace [his grandfather] bought a painting from each of them.

"A year later, they brandished a piece of paper showing that one of these guys won the gold medal at the Royal College of Art. So that's my case, that it's a Hockney."

"It's not everyone would think of as a Hockney, is it? It's pre-splash," observed Maas.

"But there is this rather wobbly signature and then of course it's been roughly sawn as if to get it into a frame."

The owner shared the backstory: "Mother had a frame so she just trimmed it around the edges so that it fitted into the frame."

To which the expert responded: "Oh perfect. Yeah that works for me.

"And it's sort of very rough and ready. You're convinced it's him," with the guest confirming he believed the claim, Mass indicated he grasped it was the "family story".

He elaborated: "Well I did do a bit of my homework having been initially incredulous.

"It turns out he was in the village near Felixstowe in 1957 which is his last year at Bradford Art College.

"And he was there with another artist called John Locker. So would that be the other chap that gave you a painting too?".

"Yes, I've got that at home," the guest confirmed.

Maas asked whether the other painting featured similar colours, and the guest affirmed it did, prompting the expert to chuckle: "I have this idea that they only had green and brown because they were broke."

The visitor concurred: "They were that poor, yes."

The BBC expert then pointed out how the artists admired John Constable, desiring to be in "Constable country".

"And they sort of made a pilgrimage and it turned out to be a wonderful place to paint and so they stayed there and hence this meeting with your grandfather.

"It's quite extraordinary. So I think it is a Hockney," he confirmed, much to the delight of his guest.

Visibly relieved, the guest beamed and expressed gratitude for Maas's validation.

"I've come round to your way of thinking. What's it worth? What do you think it's worth?" Maas probed eagerly.

The guest ventured a guess: "Well I was thinking about £10,000 I've got in my head."

Maas elaborated: "But it's pre-abstract expressionism, pre all of that, so it's almost juvenilia you might say", while the owner also likened it to "student work".

Wrapping up his assessment, Maas offered: "I think you might be right but I think it's closer to £20-30,000."

Gasping, the guest echoed: "£20-30,000? Oh God."

He doubled over, stunned, as a woman from the audience encouraged: "Just say thank you."

Following her suggestion with a grin, he replied: "Thank you for that information."

With Maas chuckling: "Yes it is information, I'm not actually giving you £30,000."

A lighter moment ensued as the guest chuckled and showed his appreciation once more, whilst the expert divulged his own reflections post-evaluation: "One of the things about Hockney that he is so instantly recognisable to most people, so when you see one that isn't, you question it really hard.

"That's the issue with that image. But it's widened my horizons immensely. I now know what an early Hockney looks like."

Antiques Roadshow is available to watch on BBC One and BBC iPlayer.