It took around 30 hours for emergency teams to be able to reach Philip Goodeve-Docker's team and airlift them to safety but Mr Goodeve-Docker died before their arrival.
The London events manager was on the unsupported crossing with experienced expedition leader Roan Hackney and Andy Norman, a former IT professional, who both remain in a "critical condition" in hospital.
More top news
The Metropolitan Police said the building material was found in the force's former training facilities.
The toddler was seriously injured when one of the cars rolled and trapped him between the vehicles in a private car park
The millionaire winner is one of 10 lucky players from the EuroMillions Mega Friday draw on 28 November.