The  watchdog has started an official investigation into revelations that a peer offered to secure meetings with ministers for a potential commercial client who wanted to lobby the government.

The investigation into , a former head of the British army, was announced on Friday.

He is the second peer now facing a conduct inquiry after revelations in , a months-long investigation by the Guardian into the commercial interests of members of parliament’s second chamber.

Lord Dannatt was secretly filmed  make introductions within the government and that he would “make a point of getting to know” the best-placed minister, in spite of rules prohibiting peers from lobbying.

He added he could easily “rub shoulders” with the right people in the Lords if he needed to approach a minister in order to promote the potential client. He also said he had previously introduced a company, in which he was given a shareholding, to a minister and civil servants.

, the Lords commissioners for standards said Dannatt was under investigation for two potential breaches of the House of Lords rules. One was the requirement for peers to “act always on their personal honour” as parliamentarians.

He is also being investigated for allegedly breaking a rule that forbids peers from seeking “to profit from membership of the house by accepting or agreeing to accept payment or other incentive or reward in return for providing parliamentary advice or services”. Under the rule, peers are banned from lobbying ministers, which includes introducing clients with commercial interests.

Dannatt has previously denied that he broke the rules of the upper chamber, saying: “I am well aware of … the Lords code of conduct … I have always acted on my personal honour.” On Friday he said he had referred himself to the Lords commissioners for standards and was unable to make any further comment as the investigation was under way.

The Lords commissioners for standards are investigating two peers after covert filming by the Guardian.

The second peer is Lord Evans of Watford, who is . The filming revealed he had offered access to ministers during discussions about a commercial deal worth tens of thousands of pounds. He was recorded explaining to undercover reporters how to approach Angela Rayner, the deputy prime minister and housing secretary. Evans has denied any wrongdoing and has not received any payments.

As part of an examination of the workings of the upper chamber, the Guardian’s undercover reporters posed as property developers who were seeking to convert high street department stores into a mixture of flats and shops, and who wanted to have their voice heard in government.

Dannatt had a meeting with the fictional property company. At the outset, Dannatt said he had to work within the rules. He said: “I have to keep myself scrupulously above board to make sure that what I’m doing is declared and is well above board and not below board.”

He added he was willing to help if he believed it was “widely in the national interest”.

As the meeting progressed, Dannatt said he could make introductions within parliament and government.

At one point, he was asked if he could help facilitate a meeting with a minister. He replied: “Yes, I mean, depending who the minister is and what the commercial plans were, I don’t see why they would not wish, if it was consistent with government policy or what you thought government policy might be if they were persuaded, why they wouldn’t want to have that meeting.”

During the meeting, he said he had previously helped a client with an introduction to a minister. He referred to a major hydroelectric plant in Sierra Leone that was being developed by an energy firm, Joule Africa. He has been an adviser to the firm since 2011.
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