The fraud trial of former ShelterBox chief executive Tom Henderson will continue with only 11 jurors after one was discharged today having been urgently admitted to hospital for tests.

Judge Gerald Gordon said the case against Henderson, 64, would continue with a diminished jury, following a restart a week ago after two other jurors had to be discharged and replaced for medical reasons.

The judge told the Old Bailey jury: "One of your number is missing. Sadly she is in hospital and the latest information is she is undergoing tests and his going to be in hospital for at least a couple of days more."

Henderson, 64, whose charity received up to £20 million from donors, is accused of handing lucrative contracts for camping and survival equipment to his son John, 35, between 2007 and 2012.

Much of the evidence being heard at the trial concerns the procurement of wood-burning Frontier stoves designed by John Henderson.

The prosecution claim the stoves were considerably more expensive than alternatives on the market and were the subject of complaints that they were not being used.

ShelterBox operations manager John Leach, who temporarily took over from Tom Henderson as acting chief executive in 2012, told the jury the stoves could potentially be fatal if used inside tents.

He added: "They were perfectly adequate outside. But they couldn't be used inside tents due to the risk of carbon monoxide.

"There were certainly opinions from the team on the ground that stoves weren't required."

But Mr Leach accepted that they were value for money and were useful "in the right circumstances."

Jurors were told that the stoves were displayed with boxes when Prince Charles and Camilla attended ShelterBox in July this year.

They were also shown to the Houses of Parliament in May 2013, the court heard.

It is claimed that when trustees of the charity began to ask questions Darren Gervis, 42, was brought in to set up "sham" companies to hide the fraud, the Old Bailey has heard.

Prosecutor Walton Hornsby has told the court how Tom Henderson "favoured his son at all costs and ultimately crossed the line into fraud."

Thomas Henderson set up the charity in his garage in 2000 to deliver humanitarian aid to the victims of man-made and natural disasters around the world and was "responsible for saving hundreds if not thousands of lives," the court has heard.

It had international affiliates in America, Australia and Europe and rapidly expanded on the back of its idea of putting all the items needed for survival into robust plastic boxes.

Thomas Henderson, 64, of Barbican Way, Helston, John Henderson, 35, of Copper Hill, Hayle, and Darren Gervis, 42, of Meadowside, Mosterton, Beaminster, Dorset, deny conspiracy to commit fraud between January 15, 2007, and December 31, 2012.

The trial continues.