Primark’s stellar first-quarter trading results have been somewhat overshadowed this week by the revelation that one of its suppliers has allegedly employed illegal immigrants in sweatshop conditions in Manchester.

Inevitably, the knives are out for Primark. Its success, coupled with the rock-bottom prices it offers, makes it an obvious target, much in the same way as US fashion giant Gap has been in the past. The same investigative journalism team that alleged bad practice by a Primark supplier based in India last year is behind the present revelations.

Last year’s claims in relation to India sparked argument – and sympathy from some retailers - that it was difficult to police suppliers in other countries, especially those in emerging markets who sub-contract.

However, on this occasion the alleged sweatshop practices and employment of illegal immigrants happened much closer to home. Too close to home for Primark.

The secretly filmed footage, which appeared on BBC News on Monday, was damning. The conditions unthinkable and plain to see. Primark is rightly embarrassed and apologetic to the innocent staff members at the supplier, which denies the claims.

However, what appears equally worrying is that the supplier in question was audited back in April and again in December, when the auditor “uncovered matters” that the supplier was supposed to remedy, according to Primark. “The audit process did not, however, discover all of the apparent practices portrayed by the BBC,” it said.

On Monday, Primark immediately said it had launched an investigation in to the claims and is examining whether, in this particular case, their auditing process has let them down.

The situation also leaves Primark in a difficult situation and gives other retailers cause to think about what they would do in a similar situation.

Primark is criticised if they are seen to have allowed the situation to continue and they will be criticised for displacing the workers if they close a factory down. They are damned if they do and damned if they don’t. The only solution is to not let the situation get to that stage in the first place.

What is clear is that Primark, which takes a firm stance on its ethical trading policy in theory, needs to lead the way on making its auditing process firmer and more transparent – not just to placate the Ethical Trading Initiative, but because the retailer’s reputation is at stake.

Like Gap, Primark keeps a very low profile. It would do well to shout more about the steps it takes to avoid situations like this.

Whether the latest revelations will have an adverse impact on Primark’s customers is debatable. Judging by the proliferation of Primark shopping bags on the high street over the past few months and by today’s positive sales announcement, last year’s expose did not damage its shoppers’ loyalty. However, the latest revelations, taking place in Primark’s backyard in Manchester, may stick in shoppers’ minds.

Even if Primark is somewhat immune to the present climate, another allegation like this could prove damaging.