The prominent businesswoman Amanda Staveley exaggerated the importance of her role in securing the billions of pounds that saved Barclays during the financial crisis, the high court has heard.

Staveley is suing Barclays for up to £1.5bn after her client, Sheikh Mansour bin Zayed Al Nahyan of Abu Dhabi, invested £3.25bn as part of an emergency fundraising 12 years ago.

She claims she is owed the massive payout because her firm, PCP Capital Partners, was more than a facilitator on the deal, acting as a private equity company in its own right. PCP also claims it missed out on fees.

Jeffery Onions QC, who is leading Barclays’ legal team, told the court: “To describe this as PCP’s deal is a classic example of form over substance.”

Supporting legal documents filed by Barclays in the case add: “On PCP’s own case, it adhered to none of the ordinary conventions of [a private equity firm]: it had no pre-established fund, no commitments of equity capital at all, and no arrangements for its own remuneration. It had not even started looking for debt financing.”

The claims were made as Barclays tried to undermine Staveley on the second day of what is expected to be a two-month trial. The financier has accused the bank of concealing that it was offering her “manifestly worse terms” compared with those given to Barclays’ largest investor, the state of Qatar, which received £346m in fees and an unsecured £2bn loan from the bank.