Aired almost exactly two years after the ill-fated broadcast of A Mission to Prey, RTÉ's A Breach of Trust investigation may well be remembered as the moment the broadcaster restored its reputation for exposing scandals, not causing them.

The creche mistreatment documentary attracted an average of 622,000 viewers, or a 39 per cent share of the total audience watching television at the time, with the ratings peaking at 708,000 during the programme.

A Breach of Trust, presented as part of Prime Time and followed by a studio discussion, isn't the first report to be produced by RTÉ's new investigations unit, but it is its first landmark one.

Public interest in the childcare standards investigation was stoked six days before the programme was broadcast, when RTÉ released a statement that it was liaising with the parents of the children, the creches featured, the Health Service Executive and gardaí in relation to the programme's contents.

Rigorous production and editorial standards had been observed, it was careful to note.

Kevin Bakhurst, the managing director of news and current affairs at RTÉ since last September, has inherited a team of journalists who are all too aware of the risks of getting it wrong, having watched colleagues depart the organisation and the institution of RTÉ taking a public battering in the wake of the libellous A Mission to Prey.

Confirmation of the documentary’s broadcast on Tuesday only came hours before the transmission time.

Updates on the to-and-fro between RTÉ, the parents, the creches and the authorities, while essential to minimise the risk of any untoward fallout, probably also helped swell the viewership.

In recent weeks, editions of Prime Time have attracted ratings in the 300,000s.

However, news audiences have softened since the peak of the financial crisis: the most-watched Prime Time Investigates was a December 2010 report on property developers that attracted 803,000 viewers.

By using undercover reporters to detect and reveal mistreatment in a care setting, A Breach of Trust harks back to Prime Time Investigations: Home Truths, RTÉ's awardwinning investigation into the Leas Cross nursing home in 2005, which led to the establishment of a commission of inquiry.

RTÉ axed Prime Time Investigates as a regular programme strand last November, but the positive part of its legacy lives on through the work of the A Breach of Trust team, led by reporter Oonagh Smyth, Samantha Bourke, Clare Killane and the head of the investigations unit, Paul Maguire.