Step by step in 35C heat, we trace last known hours of Mail's missing health guru

It’s become the most perplexing - and worrying - lunchtime walk in recent memory.

Where did celebrated Mail columnist and TV doctor Michael Mosley go after he cheerfully said goodbye to his wife, Dr Clare Bailey, on Wednesday afternoon?

Yesterday the Mail retraced his steps in extensive detail to try and find some answers to the question troubling the whole nation.

The couple had arrived by water taxi at the secluded St Nicholas Beach on this beautiful Greek island of just 26 square miles. Then, after paying 15 euros for two blue sunbeds, they spent the morning relaxing and swimming in the clear waters of the Aegean Sea – and, wherever possible, trying to stay cool.

With the sun hammering down from a cloudless sky and barely a breeze, the temperature was a blistering 35c.

Bar owner Chrisa Zauroudi, 33, remembers seeing Dr Mosley and Clare as they relaxed beneath their umbrella, which was blue to match the sunbeds.

‘At one point he got up and walked towards the stairs and then he walked back towards his wife. There was nothing strange at all about them – they seemed like any other couple,’ she told us.

‘What I do remember is that it was very hot – unusually hot for this time of year.’

And that’s when Dr Mosley did something that surprised her.

‘He got up, walked past the bar and looked at the drinks menu – before heading to the steps that go up the cliff,’ Ms Zauroudi continued. ‘He was carrying a purple umbrella. I did think it was strange to be heading off at that time of the day as it was so hot. The last I saw, he was walking up the steps.’

We now know that Dr Mosley was planning to walk to where the couple had been staying in Symi Town, close to the clock tower in the centre of the picturesque main settlement on the island.

The walk itself, perhaps a distance of three miles, takes only an hour – which makes his disappearance all the harder to understand.

My photographer and I set off from the same pebble beach at exactly the same time as Dr Mosley. Once again, the sun was blazing and, as on Wednesday, the authorities warned of extreme temperatures.

The walk up from the beach starts with 100 steps carved into the cliff face, a climb that takes your breath away in the heat. I was starting to sweat as we reached the headland five minutes later.

From there, 150 feet up, St Nicholas Beach is clearly visible below. It’s thought that Dr Mosley was standing on this spot when Clare saw him for the last time.

Then he turned round and continued along the winding track towards the fishing village of Pedi, skirting the coast on one side and clinging to the mountains on the other.

Aside from sparse wild heather, the landscape is harsh, with barren grey hillsides tumbling to the sea below.

Had Dr Mosley ‘slipped, tripped or fallen’ as the police fear? Or was he bitten by a snake, another plausible theory?

It’s unlikely he met anyone on the walk along the cove to Pedi: a smattering of white and yellow houses by the water’s edge. Described as one of the last unspoilt islands in the Aegean, Symi is not crowded.

We saw no one on our walk. And Pedi, too, seemed empty – until, 15 minutes after setting off, we walked into the Kamares café, the first commercial building Dr Mosley would have passed, and found a group of policemen. They were discussing a breakthrough.

The cafe’s CCTV coverage – seen by the Mail – clearly shows the health expert walking past on the road outside at 1.42pm.

In the footage, he is wearing the same blue shirt and shorts and, crucially, is carrying the distinctive purple umbrella or parasol he was holding as he left the beach.

Dr Mosley was again captured on camera a few moments later as he walked down Pedi’s main street – and for a third time by the CCTV of the Blue Corner Cafe at the other end. The owners have kindly allowed us to use some footage, which can now be seen on MailOnline.

And there the trail goes cold. It was not yet 2pm, almost half an hour after we set off.

A handful of yachts lay at anchor in the bay. Did Dr Mosley take a boat for some reason - another water taxi, perhaps? The Greek police are investigating.

Did he head for the main road and continue the walk to Symi, some 40 minutes’ distance?

On the road out of Pedi, we passed a bus stop where a woman was certain she saw Dr Mosley at about 2pm on Wednesday afternoon. She told the police he had been asking what time the buses ran to Symi Town, but her story has not yet been corroborated.

It is possible, too, that the health expert chose a more adventurous route and attempted to cut across more rugged countryside.

Now the authorities are searching the mountainous terrain that separates Pedi from Symi town. When we looked there was no sign of any viable track: A mountain goat would struggle.

Perhaps in such extreme temperatures, he was tempted to take a swim in the invitingly blue sea – although doing so in such conditions can be dangerous.

The water remains cool despite the sunshine and can shock the body, as Dr Mosley himself found on an earlier occasion.

In 2017, he woke up in Truro Hospital after swimming in cold water off the coast of Cornwall – and blacking out.

He had suffered a ‘transient ischaemic attack’, sometimes known as a mini-stroke, that wiped his memory for a period. He made a full recovery.

Further along the high street is the Katsaras restaurant. It’s to here that Dr Mosley’s wife, Clare, rushed on Wednesday night when footage emerged of a man bearing a striking resemblance to her husband. It was a false alarm.

At the end of the main street, we met an emergency worker sheltering from the sun beneath a pine tree.

When I asked what he thought had happened to Dr Mosley, he took a puff on his hand-rolled cigarette before replying:

‘What do I think? I think maybe the heat got to him at some stage between the beach and Symi Town. I think he was hot, he was tired and he had some sort of episode and went into the sea to cool off and then he had a heart attack. I’m sure that in a few days we will know more. It could be very sad for his family.

‘I don’t think anything strange has happened to him. This is Symi: it’s a very small island and people just don’t disappear. There is always hope.’

Indeed there is. But as the frantic hours pass, and the mystery deepens, the concerns for Dr Mosley’s safety can only grow.