Two writs related to the sale of the company in 2005 were filed in the High Court in December.
The former Partridge shareholders, led by ex-chairman John Partridge, have issued a writ for non-payment against David Mellor and Christopher Jemmett, members of the Amor Holdings consortium which bought Partridge.
Former Heritage Secretary Mr Mellor and businessman Mr Jemmett have countered with a writ demanding the removal of their guarantor status, claiming they were misled by John Partridge as to the state of the company during negotiations for its purchase.
Legal action began after it became clear that the final payment - £1.33m - in the £14m purchase deal agreed in 2005 would not be paid.
Mr Mellor and Mr Jemmett, who bought the company with dealer and auctioneer Mark Law as part of the Amor Holdings Ltd consortium, stood as guarantors of the payment, which ATG understands should have been made on November 16.
However, they made it clear that they would not be paying because they felt they had been misled over the purchase, and they made a number of accusations concerning the manner in which the company had been run prior to their purchase of it.
ATG further understands that the previous shareholders issued a writ for payment in mid December, with Mellor and Jemmett replying with their own writ two days later.
They want to be freed from their guarantee to pay the final instalment on the grounds that the company was mismanaged over more than two decades before they bought it.
They are also arguing that they were not given a true picture of the state of the company when they bought it. They say the previous owners should have made them aware of doubts raised over the authenticity of objects sold by the firm and given more detail of the circumstances where large refunds had to be made.
More seriously, they also accuse John and Frank Partridge of fraud and being party to the counterfeiting of pieces they sold.
The Partridge family have issued a firm denial of the accusations, with Frank Partridge describing them to ATG as "absolute fantasy".
Mr Law, who became chairman of the company under the consortium, is not party to the Mellor/Jemmett writ, but remains jointly liable with them for the final payment.
It is not yet clear what action he intends to take over the matter. ATG were still hoping to talk to Mr Law and Mr Mellor at the time of going to press.
Meanwhile, Frank Partridge said that the writ issued against his father and the other former shareholders was no more than a cynical attempt to drum up a reason not to pay the guarantee: "It's an absolute tragedy that this has happened. It doesn't do the antiques world any good," he told ATG adding: "We will be answering all their allegations and if they don't pay we'll see them in court."
Whatever the outcome, this latest legal wrangle caps what has been a sorry year for Partridge Fine Art after more than a century of pre-eminence in what became known as the Palace of the Arts - the multi-storey gallery in the heart of Mayfair.
Having been put into administration in July, after Allied Irish Bank called in its loans, the removal men cleared the premises and took down the name from above the door in September.
By Ivan Macquisten