William’s asked how Kate Middleton is celebrating birthday – reply makes everyone laugh

Prince William is missing part of the birthday celebrations for his wife the Duchess of Cambridge, Kate Middleton, as he’s visiting the London Air Ambulance

The Duchess of Cambridge is celebrating her 37th birthday, but one very important person is missing out on some of the fun.

Prince William attended his first official engagement of the year today, a visit to the London Air Ambulance to coincide with him being named the patron of their 30th anniversary celebrations.

It’s a cause close to his heart as he used to work as an air ambulance pilot when the Cambridges were living in Nofolk, and he spent time meeting the people behind the vital organisation.

During the engagement one of his guests asked how Kate is spending the day – and his response is brilliant.

Clearly not wanting to give anything away, he replied: “Now that would be telling”.

The woman and other guests giggled at his response.

It’s likely that Kate will spend the day privately with her family, including Princes George and Louis and Princess Charlotte.

But over the years she’s had some very fun celebrations, including nights out with her pals, trips to the theatre and family parties

In the early days of their relationship, William reportedly surprised his then-girlfriend with a romantic candlelit dinner at the Royal Family’s Sandringham estate.

Prince William took to the skies of the capital during his visit, which comes as he is made patron of the organisation’s 30th anniversary campaign.

He flew above above the The Shard and The Gherkin before the helicopter landed on the roof of the Royal London Hospital, where William watched a training exercise simulating a stabbing incident.

The visit comes weeks after he revealed his own work as a pilot in incidents involving kids left him “feeling very sad and very down” which nearly took him “over the edge”.