Allen & Overy (A&O) and Clifford Chance (CC) have taken lead roles on one of the largest London lettings deals so far this year.

The magic circle duo have advised as the European Medicines Association (EMA) agreed a pre-let of 250,000 sq ft in a new 20-storey tower which Canary Wharf Group will start building at 25 Churchill Place on the Wharf later this year.

As part of the pre-let deal, EMA will lease the basement, promenade, ground and first nine office floors in the tower. The 25-year lease will start at £46.50 per sq ft, and the EMA has negotiated a 37-month rent free period that it will use to finance the building's fit-out.

A&O won the instruction from EMA on the deal, with a high-profile team led by real estate head Adam Cleal, real estate counsel Trevor Cosgrove and competition partner Michel Struys, while tax advice was provided by counsel Ben Eaton. The firm also advised on insurance matters.

Meanwhile, CC acted for Canary Wharf group with a team led by London real estate head Jonathan Solomon alongside tax partner Sarah Squires and senior associate Simon Gilbert.

Solomon (pictured) said: "This is probably the largest pre-let to be agreed so far this year and marks a good deal for the London real estate sector. It is an especially important deal for the Canary Wharf Group as it will enable it to complete the original plan set out for the estate."

Cleal commented: "The deal looks like it will be one of the largest lettings this year. It is good to see a major occupier like EMA committing itself to London and good for Canary Wharf to have achieved this letting too."

CC is a longstanding adviser to the Canary Wharf Group, having worked with the group for around 25 years. The firm took a lead role for the group earlier this year on JP Morgan's £495m acquisition of the 25 Bank Street building on Canary Wharf – Lehman Brothers' former London headquarters.

For more, see CC, Mayer Brown act on £495m sale of former Lehman HQ to JP Morgan.