Addleshaw Goddard has won Simons Development as a new client and is to advise on the company's largest ever project – a £100m skyscraper development to be built in the heart of Leeds.

Although the company has traditionally used Eversheds' Nottingham arm, Simons opted to change for this project after being lobbied by Addleshaw property partner Paula Dillon, who is based in the firm's Leeds arm directly opposite the planned development.

"I have known Simons for a long time, almost 15 years, and always been very friendly with them. We have never done any work for them, although we have never made a secret of wanting to," she said.

Dillon also worked alongside commercial property partner John Leake to secure the instruction, which is one of the most high profile property developments in the Yorkshire market.

She added that the firm's experience of working on the Bridgewater Place development in Leeds helped swing the instruction for the firm.

The new development, called Criterion Place, will be the tallest building in the city. Its two glass and steel towers will create 70,000sq ft of shopping, hotel, office and residential space.

"I find it quite extraordinary that our first job for them is a £100m development," Dillon added. "Developers usually give you £5,000 options to start off with, and not the highest profile deal that they have ever done."

Work starts on the development in 2006 with the completion date set for 2008.