Twenty-seven former chairs of the Local Government Group (LGG) will be among the 320 guests attending a dinner to celebrate the organisation's 50th year.
The black tie dinner will be the highlight of a four-day LGG conference at Churchill College, Cambridge University, starting on 10 April.
"We have 270 delegates, which is the maximum we can take," said course director and former chair of the LGG Christopher Robinson.
Formed in 1947, the LGG joined with the Law Society in 1976 and now has around 3,200 members.
Robinson, who was chair in 1989, said the role of local government lawyers had become more specialised and they now have to become experts in particular areas of local authority legislation.
LGG chair Peter Urwin said the organisation had kept pace with those changes through the establishment of special interest groups, although he was keen to encourage and assist solicitors to continue going into the general management of their councils.
Local government as a whole faced varied and uncertain changes in the decade ahead, added Urwin, who was confident solicitors would play a key role in shaping them.