Rushden & Diamonds initially signed defender Simon Downer over the New Year Period at the start of 2009.

Downer started his career at Leyton Orient, where he stayed between 1998 and 2004, a time which included a loan spell at Aldershot Town. He moved to Weymouth for the 2005/06 season before moving onto Grays Athletic from 2006 to 2008. After leaving Grays earlier in the 2008/09 season he had non-contract spells at Wivenhoe Town and at Sutton United prior to moving to Nene Park. Simon made his Diamonds debut in the 1-1 draw with Stevenage Borough on New Year's Day 2009.

After impressing during the remainder of the 2008-09 season he signed a one year deal with the club at the end of May 2009.

Rushden & Diamonds Manager Justin Edinburgh commented, "I'm delighted that Simon's put pen to paper for next year. As fans will have seen he is an outstanding defender and keeping him here shows our intent for next season."

After some impressive performances in defence during February 2010 won him a Player of the Month award from the Evening Telegraph, he celebrated being presented with that award by scoring his debut goal for the club in the 8-0 victory over Gateshead on 13th March 2010.

After helping the Diamonds to the end of season playoffs in 2009-10 he failed to agree terms for the following season.