Prince Philip's steely resolve will help his recovery

So the supreme effort of Tuesday could indeed have been hiding something more serious and significant.

On Monday the Duke of Edinburgh pulled out of a planned engagement so his wife went for both of them.

Those of us in London for last year's big Jubilee celebrations immediately thought back to that weekend when the duke braved the dreadful weather on the Thames, was then was whisked into hospital and missed the rest of the festivities and commemorations.

But this week, the consort to Queen Elizabeth ll, her liege man of life and limb, had just one thing in mind – to be at the next day's Service of Thanksgiving.

He made it. And we in Westminster Abbey breathed a sigh of relief as the frail but determined figure took his place.

Now, two days later, the news has to be seen as a real worry. Even though, true to sterling character, the duke was at a Buckingham Palace garden party yesterday afternoon, laughing and telling jokes.

And also true to form, Buckingham Palace confirmed the admission to the London Clinic was planned and took place soon after the garden party for today's operation and would be there for up to a fortnight, but that actually, the duke was "in very good health".

Meanwhile, as she does, the Queen was continuing with her planned appointments today – including a visit to the new BBC studios. But this can't be anything but an extremely anxious time for her.

Touchingly, just before the garden party, she also invested her husband with New Zealand's highest honour, making him an additional member of the Order of New Zealand to mark the Diamond Jubilee.

Her Majesty is the Order's sovereign and additional members are appointed to commemorate important royal, state or national occasions.

So now, what happens next? Everyone will be hoping for the best today but will also be very concerned at this latest turn in Prince Philip's health.

That he has remained so active and involved even to this great age is not unique in the modern Royal Family. His mother-in-law, the nation's much loved Queen Mother, lived until she was 101 and remained active and part of royal and national life well beyond her century. There is a true grit about them which defies what might seem to be the inevitable.

But the prince has had bouts of ill health which have removed him from the scene – often around the most high profile occasion. Apart from polo and other sporting injuries, there have been heart scares, serious infections, sudden illnesses demanding significant investigation and more than a few warnings. And even when he was obviously poorly, looked poorly and had a face of granite as he determined to carry on regardless, he denied it.

Like the time he was asked about the state of his health by an estate worker at Sandringham and he shouted (cheerfully, it's said): "Do I look bloody ill?"

Yet there have been times when he has been very ill indeed. And been intensely irritated at the fuss.

He got a nasty bladder infection during the big Jubilee weekend and was whisked from Windsor to the Edward Vll Hospital in London.

While a heart scare during the previous Christmas saw him successfully treated for a blocked coronary artery after being taken from Sandringham to Papworth Hospital in Cambridge, with chest pains.

And in August last year the prince was taken to Aberdeen Royal Infirmary as a 'precautionary measure' after becoming ill in Scotland during the Balmoral break and at the end of an intense year of Jubilee celebrations.

Now, he will spend his 92nd birthday in hospital, but hopefully recuperating.

The Duke of Edinburgh has been in pretty good health for much of his life, given a nasty attack of jaundice just after the Coronation and breaks, twists and strains, almost all related to his sporting life.

Even at nearly 92, we hope that the Duke of Edinburgh's steely resolve sees him once more on the way to recovery.