The Royal Bank of Scotland (RBS) has instructed Simmons & Simmons to defend a mammoth claim brought by property tycoon Glenn Maud over allegations of Euribor rigging.

Scheduled for its first hearing in May 2016, the row stems from Maud’s purchase of Santander’s global headquarters through his Spanish property vehicle Marme Inversiones in 2008 for £1.5bn.

Simmons is a longstanding client of RBS and was reappointed to its global panel earlier this month. However the bank has traditionally turned to Clifford Chance, Herbert Smith Freehills (HSF) and Dentons on its major disputes.

HSF is running RBS’s defence in a £4bn shareholder claim scheduled for March 2017, while Dentons is representing the bank in a £30m Libor claim brought by Property Alliance Group (PAG). The bank instructed Clifford Chance to conduct an independent review into its controversial global restructuring group in 2013, now a key feature in the PAG case.

Maud alleges RBS knew it was manipulating the European interest rate and as such the swaps he entered into with the lender should be rescinded and “damages for fraudulent or negligent misrepresentation or deceit” should be paid.

The case is likely to be the biggest case related to swaps mis-selling and Euribor rigging ever brought before the High Court, with the claim understood be valued at around £800m.

Four other banks involved in the Marme loan deal are also defendants to the claim. They are: HSH Nordbank, Bayerische Landesbank, ING Bank and Caixa D’Estalvis. The group has jointly instructed Allen & Overy, with partner Andrew Denny instructing Fountain Court’s Tim Howe QC and Adam Sher.

The dispute follows RBS being fined £95m by the European Commission in December 2013 for its involvement in a cartel that had been manipulating the interchange benchmark.RBS is expected to argue that its settlement with the commission involved no explicit admission that it manipulated the rate.

Simmons & Simmons partner Richard Bunce has instructed 3 Verulam Buildings’ Adrian Beltrami QC and Laura John for RBS.

Maud has instructed Kobre & Kim founding partner Michael Kim and partners Stephen Hayes, Andrew Stafford QC and Simon Cullingworth to bring his claim. Lead partner Hayes has instructed 4 Stone Buildings’ Richard Hill QC and Alastair Tomson.

Marme v RBS comes amid a raft of civil litigation brought against UK banks to try to get courts to set aside historic contracts based on Libor or Euribor rates.

For example Barclays has settled two large claims brought over Libor rigging related swaps mis-selling in the last two years: Guardian Care Homes and Rhino Enterprises.

RBS has launched a counterclaim against Marme, filed last December, claiming Maud did not pay a €5m fee related to the swap after Marme was entered into voluntary insolvency proceedings. The bank has again instructed Simmons & Simmons on its claim.

The legal line-up

For the claimant, Marme Inversiones

4 Stone Buildings’ Richard Hill QC and Alastair Tomson, instructed by Kobre & Kim partners Stephen Hayes, Michael Kim, Andrew Stafford QC and Simon Cullingworth

For the first defendant, RBS

3 Verulam Buildings’ Adrian Beltrami QC and Laura John, instructed by Simmons & Simmons partner Richard Bunce

For the second, third, fourth and fifth defendants, HSH Nordbank AG, Bayerische Landesbank, ING Bank and Caixa D’Estalvis

Fountain Court’s Tim Howe QC and Adam Sher, instructed by Allen & Overy partner Andrew Denny