Part-time William works just 80 HOURS a month but he does have to fit in two royal duties as well

He has been stung by recent criticism that he is 'workshy' and a 'reluctant royal'.

So sources close to Prince William spoke out in his defence yesterday, describing him as a 'modern working father and husband'.

A senior aide also revealed that the future king works an average of 80 hours a month so he can combine his royal and charity work with his job as an air ambulance pilot.

Claiming the Duke of Cambridge's hours were in line with Civil Aviation Authority regulations, the aide insisted he had the backing of both his grandmother and father. 

Pilot: Prince William in the cockpit of an air ambulance pilot; bosses have praised his contribution

'It's a demanding role involving both day and night shifts,' said the source. 

'But the Duke relishes the challenge of being a modern working father and husband, combining his royal and charitable duties with this work as an air ambulance pilot.'

The prince has so far carried out just two official engagements this year.

 In a sign of just how rattled the royal household has become by repeated attacks on his commitment, William's bosses at the East Anglian Air Ambulance (EAAA) service also spoke up to insist he is doing 'a very important job'.

A spokesman for the charity maintained that the future king, who has worked as a pilot since last July, was 'very much part of the team'. 

William's public role has been subject to increasing scrutiny after it emerged that his 94-year-old grandfather, Prince Philip, undertook more official engagements than the young royals put together.