"The nature of festival and event work is such that we often travel sleeping on coaches through the night with an early morning pre-event start – it is the nature of the business … It's hard work and not for the faint-hearted.
"We had staff travel from several locations and some arrived earlier than others at the meeting point, which I believe was London Bridge [pictured left], which was why some had to hang around. This is an unfortunate set of circumstances but not lack of care on the part of CPUK."
The company said it had spent up to £220 on sponsoring security training licences for each participant and that boots and combat trousers cost more than £100.
The charity Tomorrow's People, which set up the placements at Close Protection under the work programme, said it would review the situation, but stressed that unpaid work was valuable and made people more employable. Tomorrow's People is one of eight youth charities that were supported in the Guardian and Observer's Christmas appeal last year.
Abi Levitt, director of development services at the charity, said: "We have been unable to verify the accuracy of the situation with either the people on work experience or the business concerned.
"We will undertake a review of the situation as matter of urgency. Tomorrow's People believes strongly in the value of work experience in helping people to build the skills, confidence and CV they need to get and keep a job and we have an exemplary record going back nearly 30 years for our work with the long-term unemployed."