Catherine's parents Carole and Michael Middleton are close to the royal family
Catherine's parents Carole and Michael Middleton are close to the royal family AFP News

The family firm that turned the parents of Princess Catherine -- the wife of the heir to the British throne -- into millionaires left debts of nearly GBP2.6 million ($3.2 million) when it collapsed last month, a report by insolvency specialists has revealed.

The unpaid bills left by the pandemic-hit firm's collapse include over GBP600,000 in unpaid tax.

Party Pieces, a celebration paraphernalia mail order business, was built up by Catherine's parents Carole and Michael Middleton.

Since their daughter's marriage in 2011 to Prince William, they have become close to the royal family and are regularly invited to royal events and gatherings.

The firm was launched in 1987 after Carole Middleton, 68, searched for ideas for her daughter's fifth birthday.

It grew into a successful business and generated significant wealth for the Middletons, who in 2012 purchased a GBP4.7-million mansion west of London near the royal family's Windsor estate.

At its height, Party Pieces was said to be worth GBP44 million.

Catherine worked for the firm as a website designer and photographer before her marriage to William.

However, after unpaid suppliers threatened legal action earlier this year, administrators were appointed last month and the business was immediately sold to UK entrepreneur James Sinclair for an undisclosed sum.

Will Wright, of administrators Interparty Advisory, said Party Pieces had been "impacted profoundly by the effects of the pandemic and the ensuing restrictions on social gatherings."

A report from the administrators said the firm was GBP2.59 million short of what it needed to clear its debts.

Among those left out of pocket by the firm's collapse are multiple suppliers and the UK tax authorities, who are owed GBP612,685.