LONDON: An apology in the UK's Sunday newspapers is unlikely to be enough to rebuild public trust in bank brand HSBC, which has in the past week "stumbled into a political firestorm".

The Financial Times charted how the publication of details alleging the bank's Swiss subsidiary helped wealthy clients evade tax had led to a major political row in the UK, with questions being asked about the role of the UK's tax collection agency and the provenance of some of the money being donated to the governing party.

The bank is already under investigation by authorities around the world – in Argentina, Belgium and France as well as the UK – but the FT suggested the most serious threat came in the US where it could ultimately face a criminal conviction and restrictions on its US banking licence.

Full-page advertisements in UK Sunday newspapers issued "sincerest apologies" to customers, shareholders and colleagues while admitting that the standards in place today "were not universally in place" in the past.

Whether this attempt to "put the recent media coverage into context" will be enough to reverse its plummeting ratings remains to be seen.

The bank's YouGov BrandIndex rating, which measures consumers' perceptions of a brand's quality, value, reputation and satisfaction, has taken a nosedive over the past seven days.

From a high of 1.9 on 8 February, it now stands at -7.2, Marketing Week reported. This puts it 27th out of 28 of the UK's biggest banks, just ahead of RBS.

And the brand buzz score – a balance of positive or negative messages consumers have heard through news, advertising or word of mouth – had tumbled from -0.8 to -25.9 in the same period. This was more than four times worse than the score for RBS.

But Arun Melmane, an analyst at investment bank Canaccord Genuity, thought HSBC could recover if it could communicate that these events were in the past.

"This HSBC story is a legacy of what did exist in private banking before the financial crisis and that the governments around the world don't want to exist any more," he said.

"These are offences but they were quite overlooked at that time by a lot of jurisdictions due to Swiss secrecy," he added.

Data sourced from Financial Times, Reuters, Marketing Week; additional content by Warc staff