The march was part of a campaign to protect the standards of British workers. Last month construction unions called on Gerry Sutcliffe, the employment relations minister at the DTI, to introduce measures to protect British construction workers. They claimed that their members' wages and conditions were being undercut by European contractors who were bringing in staff willing to work for worse pay and conditions.
M&E union Amicus is calling on the government to abide by the European Union's Posted Workers Directive. This protects the terms and conditions of workers who are temporarily moved to another member state of the EU. It does not prevent workers benefiting if minimum terms and conditions are better in the country where they are working.
Paul Corby, national construction officer at Amicus, added that he wanted contractors to fulfil their responsibilities under the National Agreement for the Engineering Construction Industry. He said: "This lobby is about parity with the best standards in Europe."
In addition to the issue of pay, unions are concerned that health and safety standards have been compromised by the prevalence of foreign workers who do not speak English.
The unions are particularly alarmed by the number of tenders being won by Portuguese contractors. Portugal has one of the worst health and safety records in Europe.
Building disclosed last month that UCATT was concerned about the treatment of Portuguese workers at the Home Office's headquarters development in Westminster, where the contractor is French firm Bouygues.
The TUC has launched a campaign to highlight the problem of Portuguese workers being exploited when coming to work in the UK.