The duo enjoyed success during their time together at Roots Hall as Blues worked their way up in to the Championship after securing successive promotions.
And Tilson is pleased to be back working with Barrett for the first time since 2010.
“I’ve got a lot of time for Adam so I was only too happy to come and help him out when he asked,” said Tilson, who also played for Blues before becoming manager.
“It looks as though I could be coming in more regularly now and I’d certainly be very happy if that was the case.
“Adam does things the right way with his academy and I really enjoy helping to coach the youngsters so it’s something I’m really pleased to be a part of.”
Barrett opened his academy at Cedar Hall School in Thundersley last October and regularly attracts a large number of youngsters to his training sessions.
Matches have also been organised against several professional sides and many of the young footballers have been picked up by opposition teams.
Barrett wants that to keep on happening and is pleased to have taken Tilson on board.
“It’s great to have Tilly with us and it’s great news for the academy,” said the Gillingham centre-back.
“He’s very well known in the area and his training sessions are fantastic.
“We’re looking at lowering the age group that we currently cater for and Tilly will be part of that so I’m sure it will prove to be very popular.”
For more details on Barrett’s academy email email@example.com