As members of the Royal Family entered Westminster Cathedral in pairs and small groups to attend the funeral of the Duchess of Kent, those already seated rose in respect.

This gesture was observed when Princess Anne and her husband Vice Admiral Sir Timothy Lawrence arrived, and similarly when Prince William and the Princess of Wales made their entrance.

In fact, this respectful act of rising and acknowledging each arrival continued for every royal present, from the King to the disgraced Prince Andrew and the Duchess of York.

If anything can sum up Charles’s dilemma – and despair – over what to do about his brother and his equally toxic former sister–in–law, it was laid out for him by that grieving congregation.

Affection and admiration for the royals is undimmed but the presence of the Yorks, even at a family funeral, risks both. Standing up for the Yorks, one significant figure at the service told me, was about support for the monarchy not the couple themselves.

Had The Mail on Sunday broken its story about Fergie’s groveling and gushing email to the sex offender and her ‘supreme friend’ Jeffrey Epstein a week earlier, it is not difficult to imagine an entirely different and less deferential instinct seizing the mourners.

Close friends of the King acknowledge that Charles’s Christian outlook and sense of fair play have taken a substantial knock as revelation after revelation of the sordid Epstein affair heaps yet more embarrassment on an institution that depends so much on public esteem.

If anything, his position on Andrew since succeeding his mother as sovereign has become more intractable, not less. As Prince of Wales, he merely had his fraternal bonds – albeit the two are not close – to wrestle with. Now he has to balance those with his duty as monarch in doing the right thing for the country.

His critics accuse him of dithering, a lack of grip and an absence of decisiveness. Mischievous voices suggest that Prince William would take a firmer line with his errant uncle. Friends of the King insist this is not the case and that father and son are ‘in lockstep’ over finding a solution to the Andrew and Fergie problem.

So, what are the options open to the King and what realistically can he do?

Removing Andrew and his wife from those few public–facing events he is permitted to attend seems the very least he can do. Church services would seem to be the most conspicuous. But an outright ban on the couple attending to their religious devotions might also trigger a backlash.

As one of the King’s supporters says: ‘There is something uncomfortable about the head of the Church of England refusing to allow someone to say their prayers, and that’s before you consider that person is the monarch’s own flesh and blood.’

Others, too, are uneasy. ‘Imagine,’ says a courtier, ‘if Prince Andrew had been photographed riding a horse or playing golf on the day the rest of the Royal Family were saying farewell to the Duchess of Kent. Would that be a good look?’

All the same, it is unlikely that either the duke or duchess will be allowed to repeat their attention–seeking presence – as witnessed last week – at any future public royal function.

One frequent demand has been for the King to strip his brother of the one title remaining to him, his royal dukedom. This was conferred on him by the late Queen Elizabeth on his wedding day in 1986. Because she never remarried, his ex–wife continues to use the duchess title 29 years after they divorced. And ever since it has been a lucrative honorific for her.

Opponents caution that Andrew, who has already lost his HRH style along with his military titles, would then simply resort to his birth title of prince. ‘In some eyes a royal prince sounds grander and more important than a mere duke,’ an insider tells me. ‘It’s a case of being careful what you wish for.’

There is one shiny bauble that has not been prised from Andrew, his membership of the Order of the Garter, the oldest and most distinguished order of chivalry.

He has, however, been deprived of publicly displaying his association with the order and does not attend the annual procession of costumed garter knights in Windsor, although he is permitted to join the lunch that follows.

Members have been struck off before, but conventionally only for an act of treason or for taking up arms against the Crown. During the Second World War, Japan’s Emperor Hirohito had his garter ‘colours’ removed from St George’s Chapel in Windsor, but these were restored along with his knighthood in 1971.

As the Daily Mail reported this week, there have been calls for the Yorks to be banished, exiled from this country even. But how could they be and where would they go?

Perhaps the most troubling aspect – and greatest source of public disaffection – is Andrew (and Fergie’s) continued occupation of palatial Royal Lodge in Windsor Great Park. To many the 30–room mansion symbolises his most obvious vestige of royal privilege and entitlement. As we have reported, the King has tried every available avenue, from cutting off his private funding and withdrawing his security, to trying to persuade him to downsize from the historic house.

He has, though, stubbornly refused all offers of alternative accommodation. A figure close to the discussions says: ‘Like any private tenant he has rights and cannot be removed as long as he pays his bills and meets the obligations of ownership.’

Since he was last approached on the matter, another property on the Windsor estate has become vacant, Adelaide Cottage, until recently William and Kate’s home.

Might it tempt the duke and thus take the pressure off the King? Not according to Andrew’s supporters. ‘He refuses to leave because to do so would be an admission of guilt and downsizing a punishment,’ says one.

Part of the problem is that Andrew was insulted by efforts to persuade him to move into Harry and Meghan’s former house, Frogmore Cottage.

William’s old home is a more prestigious address. But as one insider wearily put it: ‘It’s up to the duke. And he could save face still by graciously consenting to the move.’

According to this theory Andrew would agree to leave and allow his daughter Princess Beatrice and her husband and two children to take over Royal Lodge, permitting him visiting rights.

All this is bound up in what goes to the heart of the Andrew crisis. He has always denied the claims made against him by Epstein’s former sex–slave Virginia Giuffre: that as a teenager she was trafficked to the prince for sexual encounters on three separate occasions.

But however much Andrew proclaims his innocence in such matters, the duke and duchess are haemorrhaging public support for the royals. To many they are, at the very least, a couple who through spectacular bad judgment continued to maintain a friendship with a paedophile after both had sworn to cut him out of their lives.

That alone, so the argument goes, makes them unsuitable occupants of a house once home to the Queen Mother.

There is, however, one worrying aspect to the affair: if he is pushed too far how might Andrew react? Would he follow his nephew’s lead and write a memoir which could, potentially, be even more devastating for the royals than Prince Harry’s book?

And then there is the issue of the duke’s welfare. There has been talk of the impact the controversy has had on him.

At the same time courtiers are uneasy about how the Epstein scandal continues to poison attitudes towards the Royal Family across middle England.

Even now, some still cling to the hope that Andrew will do the decent thing, withdraw completely from royal life and give up his luxury home and trappings. ‘It is not too late. If he started an animal sanctuary, for instance, he would, in time, begin to earn some public respect,’ says an old friend.

And if he doesn’t, can Charles bring himself to sever all links with the brother who for 22 years was his immediate heir? Can he be firm without being cruel? With more possibly to come out about Andrew and Epstein, his legacy as monarch may depend on it.