This morning protests were staged at building jobs being run by M&E firms T Clarke, Shepherd and Balfour Beatty Engineering Services.

Several hundred electricians, members of the country’s largest trade union Unite, staged a protest at the big Park House shopping centre job on London’s Oxford Street.

The protest went ahead despite pleas from Scotland Yard to call it off after complaints from neighbouring stores, and resulted in a strong police presence.

Park House was targeted as its major M&E package contractor, T Clarke, is one of eight breakaway building services firms seeking to impose a new working rule agreement called BESNA.

In Liverpool, up to 100 workers were reported to be planning protests this morning outside the big central library site where Shepherd Engineering is working.

And in Scotland electricians protested outside Balfour Beatty Engineering Services’ job at Cambuslang fire station in Lanarkshire.

Unions claim moves to combine five existing working rule agreements into a single deal will erode wages and conditions, by introducing a semi-skilled rate for installers.

This new installer grade will be below a fully qualified electrician pay rate.

Unite regional officer, Guy Langston, said: “London construction workers have made it clear they will not accept a pay cut.

“They have been protesting for weeks and will not stop until their employers have returned to the negotiating table for a constructive dialogue.”

Eight rebel M&E contractors are backing the agreement, although last week contractor MJN Colston broke ranks and said it would delay forcing through the proposed agreement.

Blane Judd, chief executive of the Heating and Ventilating Contractors’ Association, said on behalf of the major contractors: “MJN Colston have made a statement to us that they have not turned their back on the BESNA as being promoted by the union but will be moving at a slower pace than the other seven for operational reasons.”

He added: “We are somewhat surprised at the reaction of these activists who seem to have misinterpreted the terms and conditions of this new agreement.

“The facts are that there will be no job losses or redundancies as a result of the introduction of this agreement.

“Electrical operatives’ pay will remain the same and plumbing and mechanical workers will receive an increase to bring them in line with their colleagues.”

Judd said: “There are no changes to pension, sick pay, insurance or Bupa. Holiday will be standardised which will increase electricians’ holiday entitlement by one day.”

Electrical and mechanical workers have until 7 December to sign the new agreement with a view to contractors implementing it in March.