Prince William and eldest son Prince George have offered the biggest clue yet that the Princess of Wales may be on the mend.

The Prince of Wales and his son were spotted in the grandstand cheering on William’s football team Aston Villa at Birmingham’s Villa Park on Thursday night (British time).

With both royals sporting blue and maroon Aston Villa scarfs, they celebrated the club’s 2-1 win against Lille.

It is the first sighting of William or any of his immediate family in weeks, since wife Kate’s shock statement last month that she was being treated for an unspecified form of cancer.

The royal couple and their children – George and younger siblings Princess Charlotte and Prince Louis – retreated to their country residence in Norfolk after Kate’s video statement.

“I am now in the early stages of that treatment,” she said.

“For everyone facing this disease, in whatever form, please do not lose faith or hope. You are not alone.

“William and I have been doing everything we can to process and manage this privately for the sake of our young family. It has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK.”

Following the statement, the princess said she and her family needed “some time, space and privacy”.

Kate’s statement, which came after weeks of frenzied speculation about her health, coincided with holidays for the Wales children. They are not due back at their school, near the family’s home on the Windsor Castle estate, until April 17.

Prince William has also taken more time out from official duties to be with his family, although he is expected to return from next week.

In another optimistic sign for the Wales family, he was reportedly spotted on an unusual public outing with Carole Middleton last weekend. Daily Mail royal correspondent Richard Eden reports that William and his mother-in-law were seen grabbing a drink at a pub.

“I’m told he popped into a pub in North Norfolk at the weekend with his mother-in-law, who is said to have been staying with the Prince and Princess of Wales for Easter,” Eden reported on Wednesday (British time)

“It was all very low-key with no great fanfare. He just walked in and through the pub. He appeared to be with Carole Middleton,” a patron told Eden.

The twin outings come as polling finds that Kate – who has been largely out of the public eye since Christmas – is Britain’s most popular royal. The YouGov survey found that 76 per cent of Britons said they had a positive view of the Princess of Wales, up six points since the start of the year.

Fortunately for the future monarch, William is almost as popular, at 73 per cent.

The King is also broadly popular (with a 63 per cent rating), while the Queen – once broadly disliked in Britain – found favour with 50 per cent of respondents.

The King’s estranged younger son, Prince Harry, and his wife Meghan Markle remain unpopular. Only 31 per cent have a positive opinion of Harry, while just 26 per cent feel the same way about Meghan.

They can take some comfort in remaining more popular than Harry’s uncle, the King’s younger brother Prince Andrew. He is the royal family’s least popular member, with just 6 per cent of Britons declaring a positive view.