A five week fraud trial of ShelterBox's founder and former chief executive has heard further allegations that he gave large sums of company money to his son.

A jury at the Old Bailey was told that Thomas Henderson, 64, used the charity's credit card to pay for hotels for him and his son John, 35, also on trial, and allegedly awarded him a contract to help him buy a house.

Last Tuesday Michael Johns, the charity's head of finance told jurors that in early 2012 he became "extremely suspicious" about a £650,000 order for camping equipment from a company linked to John Henderson.

He said it came as a "bombshell" when he discovered that John Henderson received a commission on every item ordered, and added: "My immediate reaction was to say this order couldn't go ahead."

Mr Johns added: "I said I had been told that John Henderson was earning a commission on sales to ShelterBox and Tom Henderson said he wasn't aware of that.

"He spoke in a way as if to say 'kids,' the way you might tut about your children, a slightly light comment in the circumstances."

Jurors heard that the Hendersons' co-defendant Darren Gervis, 42, wrote to Mr Johns: "I incorrectly advised you that John Henderson received commission on sales to ShelterBox. Mr Henderson does receive some design commission royalties on a limited number of items but at his insistence receives no commission for any items that ShelterBox buys."

Gervis later explained he was "under stress and got confused" and confirmed that John Henderson had nothing to do with his company Found International, however the domain name for Found International was registered to Ocean Fabrications, linked to John Henderson, the court heard.

Mr Johns said the investigation was then taken over by the trustees and resulted in Tom Henderson being suspended and then dismissed in July 2012. He added that concerns about breaches of the 'related party policy' had been raised two years earlier and resulted in an enquiry by the Charity Commission.

In August 2011, the court was told, Tom Henderson used his ShelterBox credit card to pay for hotel rooms during a business trip to Hong Kong for both himself and his son costing a total of £1,376.

Mr Johns said he was "extremely concerned" and could not find any evidence the bill for John Henderson had been reimbursed.

He also said a proposed order for 2,000 tents from Found International in January 2012 was potentially a breach of policy if John Henderson was involved in the company.

Last Wednesday, former ShelterBox trustee James Kingston said he discovered a cheque for half the amount of a £534,000 contract made out to John Henderson.

He raised his concerns at a board meeting in November 2008, calling for Tom Henderson to step aside until the matter was properly investigated, but said the other trustees were "awed" by the influence of Henderson and Mr Kingston stepped down after receiving no support.

He said Henderson's "bullish" personality was advantageous in getting the charity growing, but it turned to "bullying and something destructive."

He said he only became aware of the £534,000 contract for 10,000 wood-burning stoves handed to John Henderson's company, Camping Solutions Ltd, when a cheque for £263,200 came through a branch of the bank where he worked.

The jury heard that the issue of "related party" business transactions was raised at the next board meeting, but the minutes were "whitewashed" as they didn't include any details of the discussion.

Board member Ian Munday, who gave evidence on Thursday, was one of the signatories to the cheque which had no documentation, and said "it slipped through the net."

He told the trial: "We should have noted it was a large amount of money. We should have questioned it but we didn't.

"This was a very large amount of money. It wasn't clear what it was for."

Tom Henderson said the cheque was for the advance purchase of steel for the manufacture of stoves, which was not normal practice, but it was "intimated" that the payment had actually been "used to assist with the house purchase and move by Tom's son John."

The trial heard that despite revised guidelines as to how cheques should be dealt with, Tom Henderson continued to make payments to his son without observing the new protocols.

"He said he needed to get the work done and if he went though his son it would be done but if he went through the process it would take too long," Mr Munday said.

Benjamin Spurway, the former training academy manager of ShelterBox, told the Old Bailey said he was "surprised" that most of the work on a new centre at Predannack Air Field was carried out by John Henderson.

Jurors heard marine engineer John was given responsibility for installing decking, providing an electricity generator and installing one of the building blocks for the centre.

Mr Spurway said: "I don't think I was concerned, I was surprised.

"As far as I was concerned John was a very successful marine engineer and I was like 'Why are we getting a marine engineer to do decking? Isn't there someone a bit more....?

"There were times where we questioned some of the stuff and it was like 'no, just get on with it and make it happen."

He added: "There were a lot of things we went to John for because he had the resources."

And the court heard that when Mr Spurway raised the issue of tendering for the work, Tom Henderson replied: "No it will slow things down."

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

The trial continues.