George Osborne has rebuffed criticism of his appointment as editor of the London Evening Standard, arguing that ex-ministers should still contribute to big national decisions.

The former Chancellor defended his new role in the House of Commons after Labour demanded a debate on the situation, claiming it threatened to undermine public trust in politics.

It follows the furore over Mr Osborne’s new post, which led to a complaint and questions over whether current systems for preventing conflicts of interest are robust enough.

Mr Osborne said: “In my view this Parliament is enhanced when we have people of different experience take part in our robust debate and when people who have held senior ministerial office continue to contribute to the decisions we have to make.

“But I will listen to what my colleagues have to say in this debate. I’m interested to hear.”

He started by joking that it was unfortunate that the debate was too late for the Standard’s deadline.

Cabinet Office minister Ben Gummer said that steps had already been taken to strengthen systems, but would not comment on Mr Osborne’s particular case as he did not want to pre-empt any conclusions by the Advisory Committee on Business Appointments, or Acoba, which is considering Mr Osborne’s case.

On Friday Labour lodged a complaint with the Cabinet Office, asking the Permanent Secretary to make clear whether the appointment was in breach of rules.

george osborne ES

Shadow minister Andrew Gwynne said in the Commons: “The current rules on business appointments were established to counter suspicion that the decisions and statements of serving ministers might be influenced by the hope of future rewards in the form of a job offer or other monetary gains.

“Disregarding these rules deeply undermines public trust in the democratic process and the trust of the work of a member of Parliament and in this House itself. It does a disservice to those members that respect the trust placed in them by their constituents, who spend every hour of their day fighting for their constituents’ interests, and who ensure that proper attention to the representative role of an MP is given as a vocation to public service should require.”

Acoba offers guidance on not using privileged information available to an individual from their time as a minister, on waiting for a period before starting a post – they can insist on up to two years – and on avoiding lobbying the Government in areas where a person may have insider knowledge.

Generally, the body would expect to be told of a potential appointment before it is cemented, so that they can take a judgement on the post and offer guidance on whether, for example, to recommend a period of time before starting.

But with the announcement coming just before noon on Friday, a spokeswoman from Acoba said: “We’ve confirmed that we received an application earlier this week and that we’ll consider and seek the advice from relevant government departments.”

Mr Gummer said in the Commons on Monday that Acoba had received notification of the ex-Chancellor’s new job on 13 March.

Mr Osborne, at the Treasury between 2010 and 2016, has registered a series of other jobs since leaving the front bench, including a contract with the investment company Blackrock, that will see him earn £650,000 a year for one day’s work a week.