Representing more than 355,000 construction businesses, the unprecedented coalition of trade groups descended on Number 10 to call for reforms.

The petition urges the Government to back reform of payment practices and retentions after the scale of abuse was again publicly highlighted in the wake of Carillion’s collapse.

It comes just days before the second reading of the ‘Aldous Bill’ on Friday, which proposes cash retentions be held in trust accounts, to protect the supply chain.

Support has also been given from across the construction supply chain, including house building, roofing, scaffolding, electrical, heating, plumbing, interiors and demolition.

Supporters of the Aldous Bill and the petition on fair payments also gathered outside the gates of Number 10, including business owners directly affected by Carillion’s collapse.

The Aldous Bill is supported by over 120 MPs and 76 industry trade bodies, representing over 355,000 companies and many self-employed professionals. Cross-party support for reform includes Conservatives, Labour, Liberal Democrats, SNP, DUP, Plaid Cymru and the Green Party.

Aldous said: “The industry loses around £1m for each working day, mostly from SMEs. There have been proposals to stop the abuse of retentions before, but this time there is the largest coalition on fair payments ever.”

ECA CEO Steve Bratt said: “The show of support today shows that fair payment is a top priority for our industry. We need urgent government action on payment and retentions to protect the supply chain, and to ensure our industry can deliver growth and prosperity.”

BESA CEO David Frise added: “Retentions and delayed payment put thousands of firms at risk of insolvency and undermine their efforts to invest in skills, training and improved productivity.

“The government will surely want to be seen to protect SMEs and to ensure the construction industry is sustainable so it can deliver its ambitious plans for housing and social welfare. SMEs are crucial to the government’s built environment and infrastructure programme.”