Boris Johnson and baby son Wilf are dragged on a VERY hair-raising run through field near Chequers by energetic dog Dilyn

Gasping for air as he paced through the Buckinghamshire countryside, this is Boris Johnson pushing his baby son Wilfred during an energetic run as he struggles to keep pace with his beloved dog Dilyn.

The Prime Minister was captured on camera on Saturday morning by keen runner Lizzie Evans who was taking part in a 50-kilometre ultramarathon race to help raise funds for an international children's charity.

After setting off from Princes Risborough Ms Evans, 39 was five miles into the race close to Chequers when she looked up startled to see Mr Johnson hurtling towards her as he determinedly pushed Wilfred's push chair as Jack Russell Dilyn excitedly strained at the leash.

Ms Evans told MailOnline: 'I was very shocked because I've been running close to Chequers for many years but have never come across a Prime Minister.

Boris Johnson pushes his baby son Wilfred during an energetic run as he tries to keep pace with his beloved Jack Russell Dilyn near Chequers

'Boris was going quite fast, and the baby appeared to be enjoying it too. But the dog was going the fastest and I think Mr Johnson was finding it difficult to keep up with him.'

Ms Evans revealed that as she passed Mr Johnson he shouted: 'Well done, keep going,' as she hollered back: 'You too. Well done and keep going.'

The Prime Minister was captured on camera by keen runner Lizzie Evans who was taking part in a 50-kilometre ultramarathon race 

She added: 'It was quite motivational to have that encouragement from the Prime Minister and for the rest of the race, it kept me going and smiling. 

'I kept on chuckling to myself because I never expected to run into Boris Johnson.'

Ms Evans, an occupational therapist from Aylesbury, Buckinghamshire said that while she was impressed to see Mr Johnson out running, she was less taken by his attire.

She said: 'He was running in an office shirt and what appeared to be a pair of ordinary shoes. 

'Maybe he had forgotten his running gear back at Downing Street but at least he had a pair of long shorts on, although they did look a bit odd.

'But it doesn't really matter because the most important thing is that he was out enjoying the countryside with his child and exercising so that is sending out a positive message to the country. 

'I might not agree completely with his politics but it's important for him to show the public that you need to keep fit.'

Ms Evans finished 13th in the women's section of the gruelling race.

She said: 'It was a mental and physical test that involved running over very challenging hills and can feel quite punishing. 

Carrie Johnson carries her son Wilfred as she walks with the First Lady Dr Jill Biden on a beach in Cornwall during the G7 summit

'I'm not sure what distance Boris Johnson ran but I bet it wasn't 50 kilometres.'

Earlier this year, Downing Street revealed that Mr Johnson, 57, had lost a stone since he was hospitalised with Covid-19 last April and he later famously admitted that: 'I was too fat.'

He is now regularly seen running on London's streets as part of his new fitness regime, which also involves a strict diet that has led him to cut down on carbs, chocolate and cheese, prompting him to boast that he now feels 'full of beans.'

Despite his new lifestyle, Mr Johnson joked during a recent radio interview that he still considers kebabs to be his favourite healthy meal.