Forty members of the House of Lords have been reported to parliamentary authorities, in what is believed to be one of the most wide-scale breaches of transparency rules ever reported in Westminster.

The news comes after openDemocracy revealed how dozens of Lords appear to have flouted rules by not declaring details of private companies they run.

Rules say that if a lord is a company director, they should “give a broad indication of the company’s business, where this is not self-evident from its name”. But openDemocracy found that dozens of peers have not done this.

They include Labour peer Lord Carter of Coles, who runs an offshore company called Primary Group Limited, based in the tax haven of Bermuda. Although he has declared his directorship, he has not said what the company does.

Another peer, Lord Brennan, is chairman of a private business development firm that offers to “develop and maintain our clients’ relations with governments, both in the UK and overseas”, according to its website. But the register of interest gives no details about the nature of the firm’s work.

Lord Bamford, who owns digger firm JCB and has given millions to the Conservative Party, says he is also the director of a company called Editallied Limited. But again, no further details are provided.

A formal complaint was submitted to parliamentary authorities this morning, by the former Liberal Democrat MP, Tom Brake, who is now director of Unlock Democracy.

In a letter to the Lords’ Commissioner for Standards, Brake lists 40 of the 42 peers first identified by openDemocracy, reflecting recent updates to the register of interests.

“Our democracy will benefit when a clearer explanation of peers’ business interests is provided,” Brake said. “This should already have been done.”

“The Commissioner must promptly enforce the Code of Conduct to ensure everyone knows what type of business peers are engaged in and how this might influence their activities in Parliament.”

Pickles cleared?

One of the peers named in openDemocracy’s original investigation was Eric Pickles, the chair of Westminster’s lobbying watchdog.

The Conservative lord is a director of Oakworth Services Ltd, a business he owns with his wife.

But although Pickles has declared his role in the company – which he describes as a “consultancy” – his register of interests does not state what type of consultancy work it does.

The day after openDemocracy published its report last month, the House of Lords Commissioner for Standards opened an investigation into Pickles’ conduct. But details of the investigation were kept private, with the Commissioner saying only that it related to Pickles’ register of interests.

It has now emerged that the probe was sparked after a complaint by a member of the public, who believed Pickles should have registered the clients of Oakworth Services Limited.

Pickles explained that the company does not currently have any clients or income, and has since been cleared of any wrongdoing.

But the Commissioner’s investigation did not look at the specific questions raised by openDemocracy, which concerned the omission of a “broad indication of the company’s business”.

Pickles is, therefore, included in the list of 40 peers sent to the commissioner by Brake and could face a further investigation.

He has previously told openDemocracy that he has given up all outside paid interests since he started chairing the Advisory Committee on Business Appointments (ACOBA). But he has not commented on the specific question relating to the description of Oakworth Services Limited.