Keen was born in and began his career as a trainee with Newcastle United, turning professional in August 1995. He spent four further years at Newcastle, but failed to make the first team and joined Carlisle United on a free transfer in June 1999.
He let in five goals on his Carlisle debut, a 5-2 defeat away to Halifax Town and didn't play again until the following February when he let in another four goals away to Rotherham United. On October 24 2000, Keen scored for Carlisle with a kick from his own penalty area in the 3-2 defeat away to Blackpool.
He joined Darlington on loan in March 2001, before returning to the reserves at Carlisle. He finally gained a regular place in the Carlisle side suring the 2001-02 season, but was released at the end of the season as Carlisle sought to cut costs. However, he resigned for the club before the start of the next season but after then was ousted as first choice keeper by Matt Glennon.
Carlisle were relegated to the Conference in 2004, but Keen remained with the Cumbrians until September that year when he joined fellow Conference side Scarborough on a free transfer, playing just four times before suffering a serious shoulder injury.
He left Scarborough at the end the of the 2004-05 season and was a regular in the Gateshead side during the 2005-06 season, but left to join Horden Colliery Welfare at the end of the season.
Gateshead have also pulled off a major coup by signing highly rated striker Mattie Moffat from Blyth Spartans. The Tynesiders recently put in seven days' notice for Moffat while he was still with West Auckland Town, only to learn that Blyth had got in first and completed a deal before Gateshead were given an opportunity to speak to him.
Undeterred, Gateshead followed up their interest and put in seven days' notice with Blyth last week. Their determination was rewarded when Moffat put his name to a contract this evening. In explaining why Moffat moved to Gateshead after such a short spell at Croft Park, the Tynesiders' Chairman, Graham Wood said:
"The overall financial package which we've agreed with Mattie is more or less the same as Blyth had offered him. The difference is that we demonstrated our confidence in Mattie's ability by offering him a contract which will run until the end of next season and carries an option to renew for the season after.
"He was also very impressed with the set up at Gateshead and with our plans for the future. Mattie is a big pal of West Auckland goalkeeper Mark Bell who has played a couple of loan games for Gateshead recently and I believe that Mark gave Mattie a glowing report of the set up at the International Stadium."