William stands with his mother in the Royal Box on Centre Court at Wimbledon

‘He has got to get the balance right between his flying and his royal duties. It is a niggling sore for him.

‘It is true that the Queen and the Prince of Wales are both incredibly supportive of his career and whatever decision he makes. They have made clear that it is a decision he and his wife have got to take together. He is very torn.’

My sources say that one of the others factors the prince is weighing up is his home on Anglesey, the island in North Wales, which has given himself and Kate the relative peace and anonymity they crave.

If he decides to take all or part of a new 36-month tour of duty, then he will almost certainly have to transfer to a new base in a different part of the country – very possibly Lossiemouth in remote, northern Scotland. Do he and his wife have the stomach to start again? Particularly, of course, if the couple do have a child in the immediate future, as they have both indicated they are keen to do.

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Poor Kate, who turned 30 in January, finds herself subjected to daily scrutiny over her figure and potential ‘baby bump’.

Her private office at St James’s Palace have made clear that they will not speculate on the issue, and if and when there is anything to say, an announcement will be made.

Friends of the prince say they think it is unlikely the pair would try for a baby before their upcoming Diamond Jubilee tour of Malaysia, Singapore, the Solomon Islands and Tuvalu – a gruelling ten-day tour in September that is likely to tire even those in the rudest of health.

And, like many military wives, Kate might find it a challenge starting a family in a strange town far away from her nearest and dearest. She admits that she ‘worries terribly’ whenever her husband is out on a mission.

But, friends also shrug ruefully, who knows with William? He is a prince who revels in playing his cards close to his chest.

The royal flyer also has to consider the potential public backlash that ‘jacking in’ his career at such an early stage could spark, particularly given the £800,000 of public money it took to train him.

His pilot’s training course was even given its own, slightly ostentatious codename - Golden Osprey.

But at least, unlike his father who turned 30 very much as a single man hankering after the one woman he seemingly could never have, William is settled domestically.

He is, say his friends, ‘absurdly proud’ of the way in which Kate has ‘found her feet’ as a member of the royal family, and the confidence with which she is now tackling her work – not, they stress, that William ever doubted her.
The couple will, for the time being at least, continue to conduct the vast majority of their jobs as a couple and ‘very much see themselves as a team’.

Kate is a hugely nurturing figure in William’s life who cooks his dinner, runs their house and shares his interests in walking, biking and countryside pursuits.