Born in Truro, Cornwall, Alcock started his career with the Yeovil Town youth system in 2004. At the start of the 2005–06 season Alcock was awarded a first team contract along with fellow youth teammates Tom Clarke and Jake Smeeton. Due to being over-age for playing in the youth side for Yeovil Town, he had three short-term loan spells in the 2006–07 season with Conference South side Weston-super-mare, Southern League sides Taunton Town and Tiverton Town. He made his first team debut as a substitute away at Gillingham in the final league match of the 2006–07 season. After making a breakthrough and challenging for the number one right back slot in the 2007–08 season, Alcock became a regular starter during the 2008–09 season due to injuries and suspensions concerning Lee Peltier. In May 2009, Alcock signed a new 2-year contract with Yeovil Town, and after new captainStefan Stam was dropped due to injury and poor form, Alcock was made captain for the remainder of the season. In early summer 2010, Alcock was linked with a move to championship side Norwich City but remained with Yeovil for the remainder of the season and in May 2011 was informed by the club that he was one of seven Yeovil players who would be awarded new contracts.
Peterborough United
Despite being offered a new deal at Yeovil, in July 2011 Alcock signed for Peterborough United on a three-year deal with Yeovil receiving £100,000 in compensation due to his age. Alcock made 112 appearances for Posh in all competitions over his three seasonsat the club, including winning the Football League Trophy in 2014, before being released at the end of the 2013–14 season.
Sheffield United
In July 2014, Alcock signed a two-year deal with Sheffield United. Alcock started as a regular in the side both at centre half and then in his more customary role at right back. However, after an injury he has found himself in a more peripheral role, made harder by the January arrivals of additional full backs Kieron Freeman and John Brayford. In his second season at United, Alcock again found match time hard to come by, and as a result joined fellow League One side Doncaster Rovers on a 28-day loan On 10 November 2015. The loan was made permanent on 7 January 2016.
On 1 February 2019, following his release from Cheltenham, Alcock re-signed for Yeovil Town on a contract until the end of the 2018–19 season.
Personal life
Alcock is also a keen cricketer playing for Wincanton CC in the Somerset League. Alcock studied for his A-Levels at Sexey's School in Bruton, Somerset.
