A distraught son has been left heartbroken after finding his mum and teenage sister dead inside his burger van this morning.

Tyla Wanstall arrived at his Meat 'N' Greet Snack Wagon off the Old Thanet Way in Whitstable to discover mum Leah Churchill and his "beautiful baby sister" Brooke Wanstall lifeless.

It is believed they had suffered carbon monoxide poisoning from generator fumes while decorating the unit, which is the entrance to the Benacre Riding Stables, late last night as a surprise for Tyla's 26th birthday today.

Tyla, of Whitstable Road, Faversham, has now spoken of his family's devastation over the tragic deaths, paying tribute to his 17-year-old sister and his mum, who was 50.

Speaking exclusively to KentOnline, he told how the pair had lost their lives while trying to make his birthday extra special.

"They were decking the van out inside in balloons and bunting as a birthday surprise for me, like my mum would do at home every year," he said.

"I didn't even know they were going down there last night but she must have started the petrol generator for power and to keep warm without realising the danger."

Tyla says the generator is used outside the van during working hours but kept inside overnight for security reasons.

He says he arrived at the wagon at about 8am to start work and was surprised to see his mum's car parked up outside.

"I opened the van door and and saw my mum and sister and for an instant thought they had fallen asleep," he recalled.

"I smelt fumes but it just didn't register straight away, but it became obvious they were both dead.

"I called the police and ambulance but it was the firefighters who told me it was likely carbon monoxide poisoning.

"It's heartbreaking to think they spent their last few moments just trying to put a smile on my face."

Leah lived in Wife of Bath Hill on the London Road Estate in Canterbury and was a mum of four, leaving behind another daughter, Ocean, 23, and son Sonny, 12.

"She was so kind and would do anything for anyone," said Tyla, who has just had a baby boy with his partner Beth.

"She would take a homeless man in off the streets if she was allowed. Brooke was just a live-wire with a huge personality.

"Mum worked all over the place, mostly in hospitality, and used to run the Share and Coulter pub in Greenhill.

"She was helping me in the burger van a couple of days a week."

Tyla says Brooke had just left Archbishop's School in Canterbury after completing her GCSEs.

"She had her whole life in front of her," he said.

"She did really well in her grades and had just started work as a carer, which she was really enjoying. She was also due to take her driving test next week."

Brooke's sister, Ocean, added: "She tried working in the van a couple of times but that definitely wasn't for her.

"Working as a carer was what put the spring in her step and the only thing she wanted to do."

Tyla, who also works as a drum and bass MC, says the whole family is reeling from the tragedy and still trying to come to terms with what has happened.

They are planning a balloon release in memory of his mum and sister opposite Cain's amusements on Herne Bay beach at 5pm tomorrow, with everyone invited.

Tyla has also issuing a warning about the dangers of carbon monoxide poisoning.

"Mum made a fatal mistake and we don't want this to happen to anyone else," he said.

"Be aware of this thing, people. If you haven’t got a carbon monoxide alarm go and get one. It is a serious killer.

"I don’t know how we're ever going to get over this."

The deaths are expected to be reported to the coroner for a future inquest.