The agency will supply the LDA with parliamentary monitoring services to keep it abreast of events at regional development agencies outside the capital.
Set up in 2000 to drive sustainable economic growth, the LDA has a £300m budget and is answerable to Mayor Ken Livingstone. It has been involved in negotiations with businesses located in the Lea Valley area, London 2012's proposed Olympic site.
AS Biss picked up the business after a competitive pitch. Consultant Pam Learmonth leads the account.
The agency has in the past provided the LDA with advice on a project basis. The organisation is led by chief executive Manny Lewis.