Barnet Council has been ordered to pay thousands of pounds in compensation for failing to provide information on the number of agency workers it employs.

The Employment Tribunal Service found the authority had breached Agency Workers’ Regulations by failing to provide trade union Unison with the number of third party staff on its books.

Unison had asked for the information in the middle of redundancy consultations on the authority’s One Barnet outsourcing programme in March last year.

The council’s failure to provide the information, the tribunal ruled, meant 150 workers were not afforded appropriate protection from their union during subsequent redundancies.

The council was ordered to pay the staff 40 and 50 days' pay in relation to two transfers of workers and a redundancy exercise carried out last year.

The decision by the Watford tribunal was a landmark ruling as it was the first case to be brought under new rules introduced in 2011 alongside the Agency Workers’ Regulations.

Employers are required to provide information on the number of agency staff engaged in TUPE transfers - when a worker’s terms and conditions are transferred to the organisation their job is being outsourced to.

A judge in the case said the council’s inability to provide the information represented a “relatively serious failure”.

Unison said the decision has important ramifications for other unions to help them negotiate more effectively and avoid redundancies.

Barnet branch secretary John Burgess said in a statement: “We welcome this decision, which recognises the hard work of our local reps who have consistently raised the issue of agency workers data over the past three and half years.

“We repeatedly warned the council about its responsibilities to provide the agency data at a time when staff are at risk of redundancy and outsourcing. Barnet Council has become increasingly reliant on consultants and chose to ignore our attempts to resolve this matter locally.”

A Barnet Council spokesman said: “Our understanding is that Barnet is just one of many employers potentially facing legal challenge on this issue. We will obviously consider our response carefully before taking any further action given the implications the case could have across the UK.”