A High Court judge has overturned a house repossession order after declaring the lender bank misrepresented the facts in the case.
Mr Justice Deeny said no explanation has been given for a misstatement on behalf of Santander, expressing uncertainty over whether it was an honest error or someone "playing fast and loose with the truth".
The ruling came in an appeal mounted by Thomas Carlin and Maxine Hughes.
Mr Carlin and Ms Hughes were challenging a High Court Master's decision to grant possession of their home due to mortgage payment arrears.
They disputed Santander UK plc's right to enforce the mortgage because they suspected they may have transferred it away.
In a judgment given last month but only just published, Mr Justice Deeny said it was now admitted that part of an affidavit which formed part of Santander's case is "simply wrong".
According to the judge whoever supplied the information that the mortgage had not been assigned were "either being careless or untruthful and at this precise moment in time I do not know which is the case".
He said: "So the order of the court below was obtained improperly by a misrepresentation to the court, misrepresentation put by the advocate for the lender to the Master and put in a sworn affidavit."
The situation was worsened by Santander's "disregard" for the decision of an earlier judgment involving similar points, Mr Justice Deeny added.
Mr Carlin, who appeared as a personal litigant, argued for the order to be struck out on the basis of untruth.
"The court of course recognises that everybody makes errors," Mr Justice Deeny acknowledged.
"They should not make them on affidavits, but at this point I do not know whether this was an honest error, I do not know whether somebody was playing fast and loose with the truth."
Striking out the possession order, he said: "No explanation of the earlier misstatement is given in the new affidavit.
"What is certainly the case is that Santander have been in breach of the directions of the court, they have been in breach of the (earlier) judgment... and they obtained an order by at least, as I said earlier, misrepresenting the facts to the Master."