Helen Golder of Hoghton, near Chorley, was among those who died when the 10 seater Toyota vehicle crashed on June 30 last year.

The tyre which burst was in 'poor condition' and looked unlike the other three tyres on the vehicle, the Gloucester inquest was told.

The vehicle had been hired at the last minute by a local tour operator because the scheduled minibus had not returned from a service.

After the tragedy the owner of the tour company admitted the bus had not had any safety checks before the trip.

Gloucestershire coroner Alan Crickmore recorded accidental death verdicts on Ms Golder, 33, and colleagues Elizabeth Wilson, 31, from London and Susan Andrews, 32, of Naunton Lane, Leckhampton, Cheltenham.

All three were working as volunteers for heart specialist Sir Magdi Yacoub's charity Chain of Hope, which performs cardiac surgery in developing countries, the inquest was told.

When tragedy struck they were on a trip from the capital Maputo to the Kruger National Park in South Africa when tragedy struck.

At the time of the crash Ms Golder, a former pupil of Gregson Lane Primary School, Walton-le-Dale High School, and Runshaw College, Leyland, was employed by the Royal Brompton & Harefield NHS Trust. She had been working in London for three years.

In a statement read to the inquest another passenger on the bus, Clive Kidd, told of the horrific moment when the tyre burst.

Only the driver and front seat passenger were wearing seat belts – a legal requirement in Mozambique – but the rest of the passengers were not using their lap belts, he said.

He described the driver as "okay," not weaving in and out of traffic but not dawdling either.

Ms Golder and Ms Wilson were certified dead at the scene and Ms Andrews died two days later in hospital in Johannesburg when her life support machine was switched off.

Mr Crickmore said: "These were three young women who were undertaking charitable work and sadly lost their lives during the course of those acts," he concluded.

"They had no input into the quality of the vehicle in which they were travelling.

"Consequently, effectively, what happened was something over which they certainly had no control.

"Whether the operator of the vehicle had maintained that vehicle to proper standard and therefore whether the operator of the vehicle had some control over what happened I will never know."