He was appointed number two to Andy Hessenthaler but put in for the role on the recommendation of Stimson.
"When Mark left he said 'go for it'. I was disappointed I didn't get it. But I am looking forward to working alongside Andy," he told BBC Radio Kent.
"Mark dropped my name in which I appreciated. He made it very easy for me, so I did. But Andy's the manager and I'm the number two and I'm fine with that.
There's trust between me and Mark straight away. Mark Stimson put Mark Robson's name forward and rightly so, he's a top coach
New Gillingham boss Andy Hessenthaler
"Andy is very much going to involve me, I am pleased about that, and I am really looking forward to it.
"I was always given a good hand by Mark and I know Andy is going to be the same. Andy is going to pick the team and I will do all I can to assist him in that role."
Hessenthaler said he had no issue with working alongside someone who applied for his job.
He said: "There's trust between me and Mark straight away. Mark Stimson put Mark Robson's name forward and rightly so, he's a top coach. I know he wanted the job but there's no problem, we're a partnership."
Source: BBC Sport
Source: BBC Sport