by Notts County on 18 February 2012. Third spell at Barnet Allen was appointed caretaker manager of Barnet on 16 April 2012 for the last three games of the 2011–12 season, replacing Lawrie Sanchez. Barnet managed two wins under Allen's managership, finished 22nd and avoided relegation from League Two with a 2–1 win on 5 May 2012 on the last day of the season, against Burton Albion. Following the end of the season, Allen's contract ended. Gillingham On 5 July 2012, Allen was appointed manager of Gillingham signing a two-year contract. His first match as Gillingham manager came on 14 August 2012, a 2–1 away win against Bristol City in the League Cup. While at Gillingham, Allen oversaw the Kent side's best ever start to a league season. He also broke the club record for most away wins in a football league season with a 1–0 win over Chesterfield, the eleventh of the season on 23 February 2013. On 6 April 2013 Gillingham secured promotion to League One, Allen's first ever promotion in his career as a manager. They secured the League Two title with a 2–2 draw against AFC Wimbledon at Priestfield on 20 April. On 20 May 2013, Allen was crowned League 2 Manager of the Year by the LMA for his achievements with the club. Allen was sacked by Gillingham in October 2013 after sixteen months in charge. Gillingham had won just two games from eleven played on their return to League One. Fourth spell at Barnet Allen was appointed head coach of Barnet on 19 March 2014 until the end of the 2014–15 season, marking his fourth spell at the club. He coached them to the 2014–15 Football Conference championship on 25 April 2015 to secure promotion to League Two. Barnet comfortably avoided relegation in their first season back in League Two, finishing 15th. However, despite the Bees starting the 2016–17 season just outside the play-off zone in 8th place, Allen made an unexpected request to terminate his contract to join National League side Eastleigh. The request was granted on 1 December 2016. Eastleigh On 1 December 2016, Eastleigh had confirmed that Allen had joined up with them taking the Manager's position previously help by Ronnie Moore. His first game incharge was in the FA Cup against Halifax Town which ended 3–3. This required a replay in which Eastleigh went away to Halifax and won 2–0.