The chairman of the Commons health committee has revealed his concerns over the relationship between the Care Quality Commission and the parliamentary health service ombudsman.

In a letter to James Titcombe, whose baby son Joshua died at the University Hospitals of Morecambe Bay Trust in 2008, Stephen Dorrell says he has “grave concern” over the actions of the CQC in relation to its handling of problems the trust.

He wrote to Mr Titcombe following the Grant Thornton review of the CQC’s regulatory action at Morecambe Bay.

The review, published in June, found an alleged cover-up at the CQC of a report highlighting concerns over infant deaths at Morecambe Bay.

Former CQC chief executive Cynthia Bower and health ombudsman Ann Abraham held an unminuted conversation in the summer of 2009 and this was part of the investigation by Grant Thornton.

The review examined the relationship and whether there was an inappropriate relationship between the two regulators.

But while it found no evidence to “suggest impropriety” between the CQC and the ombudsman Mr Dorrell said: “the narrative and the analysis in the report describes a state of affairs in which the CQC manifestly did not meet the test of independence of action” he would have expected.

He added: “It is a matter of grave concern, for example, that the CQC north west regional team apparently downgraded the risk rating of the trust as a consequence of the decision of the ombudsman not to investigate the circumstances of your son’s death, when assurances had previously been given that the CQC would deal with systemic issues arising from the serious untoward incidents at the maternity unit at Furness.”

“In my view it is unacceptable that such interdependence between the work of an investigatory body and a regulator should ever have been allowed to arise.”

Mr Titcombe told HSJ: “I’m pleased Stephen Dorrell has highlighted the unacceptable interdependency that was allowed to develop between the CQC and PHSO in Joshua’s case. The fact the Grant Thornton review failed to draw this conclusion has been a source of frustration.

“It is important now that both organisations accept that what happened was unacceptable and set out clearly the steps they will take to ensure the same circumstances are never repeated.

“There should never be a trade-off between the actions of one organisation against the other.”

Former CQC chief executive Cynthia Bower said: “I don’t imagine for one moment I gave the ombudsman as assurance that we would definitely investigate.

“I’m sure I said I will take this into account when we are registering the trust. If I’d said we will definitely investigate I would have gone away and made sure we definitely investigated, I wouldn’t have just left it.

“I completely accept that’s the challenge but without recourse to the managers who were there at the time I couldn’t tell you in all honesty what involvement I had or why that particular decision was taken.”