A massive police presence controlled the protest which was showed no signs of trouble as of lunchtime today.
The marchers held a rally outside Balfour Beatty’s Blackfriars station job before moving on Parliament later today.
The March sparked a lot of interest in the City and protesters tried to encourage Balfour Beatty workers to leave the site with little success.
The official demonstration was organised by Unite against plans by leading M&E contractors to quit the industry’s pay and conditions agreement.
But rank-and-file sparks were hoping for more direct action with plans to stop work at sites.
Emails put round by organisers this week stated: “This dispute will be won by stopping production on the big jobs – not by appealing to the good nature of politicians
“If we have got thousands of angry sparks in the middle of The City on 9th November – we should do more than just listen to speeches.
“We should physically close down the sites – The Pinnacle, The Shard, Blackfriars Station and Crossrail.
“This dispute has been led by the rank and file from the beginning – and we willl run it on the 9th November as well.”
The protest is also coinciding with action by students demonstrating against increases in tuition fees.
One union source said: “There is the potential for things to get a bit out of hand but hopefully everything will go smoothly and the lads will get their message across.”