The third of a hat-trick of new signings made by Martin Allen on the same day in late-July.
Nelson joined the Gills on a two-year deal and made his debut the following day, keeping a clean sheet, in the pre-season friendly defeat of Dartford at Princes Park.
30-year-old "Nels" has previously played for Martin Allen at both Brentford and Notts County.
The Stroud born goalkeeper played for FC Battledown, Cirencester College Football Academy, Doncaster Rovers and Hucknall Town before a £10,000 transfer took him to Brentford in February 2004.
He was sent-off late-on in his Bees debut at Brighton & HA the following month but went on to play 139 times during his time at Griffin Park, which also saw him named club captain.
After being released in the summer of 2007 he joined Leyton Orient and a year later joined Glenn Roeder's Norwich City but failed to make a first-team appearance while at Carrow Road.
After a spell with Scottish Premier League outfit Aberdeen he signed for Notts County on a two-year deal in June 2010.
`On the Spot:`Q: If you were trapped in the club lift with any other player who would you choose to be with?
A: Chris Whelpdale, because if I’m going to be there for some time I need to get my head down! I’ll let him start talking and I’ll be asleep in no time – by the time I wake up I imagine it would be open.
Q: Who is the best table tennis player in the squad?
A: I haven’t seen any of them play but I’d go for Dacky [Bradley Dack] because the Chinese were great at the Olympics!
Q: You have forgotten to bring lunch to the club – you find a sandwich in the fridge, it’s not yours but you decide to eat it anyway. Who’s do you hope it is?
A: Carl Muggleton’s I think because it will be a large sandwich (Fans will need to read Carl’s `On the Spot` to get the, what appears to be, running joke).
Q: iphone or blackberry?
A: What’s a blackberry? That’s a fruit isn’t it?
Q: You accidentally dent another player’s car in the car park. What do you do?
A: Who would drive into a parked car?
Q: All of the squad are placed in a cage – who would be the last man standing?
A: Danny Jackman – no one would touch him because they wouldn’t think he was standing!
Q: What is your biggest DIY disaster?
A: Every time I pick up anything to do with DIY! Even a flat pack challenge ends up taking an hour because something will go wrong, it always does. Putting a mirror on the wall is tricky – you drill the holes, measure the distance and you think it’s right but when you put it up its out by an inch or two!
Q: What is the best match you have ever watched either on TV or live at the ground?
A: It’s got to be Man City v QPR at the end of last season – it made it even better because it was Man Utd and their fans were celebrating the title and it was cut short.
Q: You arrive home before your wife or girlfriend and she has asked you to make dinner. Do you cook or order a takeaway and pass it off as your own food?
A: I cook anyway so I would do it and she would have to wait. If she wants it before she would have to go and get it!