NUTS on the fatal Potters Bar rail crash points could have been removed with a spanner bought at any high street DIY store.
One maintenance contractor said: 'It would have to be a big one but you can buy an adjustable spanner on the high street that would do the job.'
The news contradicts Health and Safety Executive claims that vandals or saboteurs would need highly specialised equipment to remove the nuts.
The HSE appeared to rule out vandalism as the root cause of last Friday's tragedy in its interim report but it is not without precedent. British Transport Police are currently investigating allegations of tampering with switches and crossings in the King's Cross area of London.
In 1999 British Transport Police investigated vandalism to points on the East Coast Main Line at Thirsk in North Yorkshire and in 1998 nuts were removed from points at Darlington on the same line.