Allen & Overy (A&O) and Sidley Austin Brown & Wood have taken the lead roles on an innovative £20bn securitisation programme for FTSE 100 lender Northern Rock.

Sidley advised regular client Northern Rock on the formation of the special purpose vehicle Granite Master Issuer, which will be used to launch a series of mortgage-backed bonds. A&O is acting for lead arrangers Citigroup, Merrill Lynch and Barclays Capital.