Mulligan was born in Liverpool, England, but his family moved to New Zealand when he was five.[5] He returned to England at the age of 16, along with Rory Fallon, to join the youth team at Barnsley; the move had been arranged by Rory's father Kevin, who was an assistant to New Zealand head coachJohn Adshead.[6] He made his professional debut for the club under Glyn Hodges's caretaker stewardship in a 3–0 defeat to Manchester City at Oakwell on 31 October 2001.[7]Steve Parkin's "Tykes" were relegated out of the First Division at the end of the 2001–02 season, but Mulligan retained his place in the Second Division for the 2002–03 campaign. He scored his first senior goal in a 2–1 defeat at Oldham Athletic on 5 April 2003. However, he lost his first-team place under Guðjón Þórðarson early in the 2003–04 campaign and was released by Barnsley in October 2003,[8] despite having been offered a new contract just five months earlier.[9]
Doncaster Rovers
Mulligan had an unsuccessful trial at Sheffield United during four months without a club.[10] He joined Third Division leaders Doncaster Rovers in February 2004,[11] initially on a match-to-match basis, then on a short-term contract,[12] before he was rewarded with a two-year contract after Doncaster won promotion as champions at the end of the 2003–04 season.[13][14] He quickly established himself at the Keepmoat Stadium, but again ran into trouble early into the 2004–05 season, being placed on the transfer list by "Donny" in November 2004.[15] He went nowhere however, and on 29 November he provided an assist in a 3–0 victory over Premier League side Aston Villa in the League Cup.[16] On 4 December, he scored two free kicks – from 25 yards (23 m) and 20 yards (18 m) – in a 2–1 win over Boston United in the FA Cup.[17] He remained a regular starter up until the end of the 2005–06 campaign. The utility player was offered a contract by managerDave Penney in the summer of 2006, but the two sides failed to agree terms.[18]
Scunthorpe United
In June 2006, Mulligan signed for League One side Scunthorpe United, having met manager Brian Laws at a M180 motorway service station to discuss the situation at Glanford Park.[19][5] He made 29 appearances throughout the 2006–07 season as Scunthorpe secured promotion as champions of League One.[5] However, he never took to the field in the Championship due to differences with manager Nigel Adkins; he had been involved in a car accident and been late to training, and also had to miss games due to international commitments.[6] He joined League Two side Grimsby Town on a one-month loan on 30 August 2007.[20] He made his debut for the "Mariners" on 2 September, in a 2–1 defeat at Shrewsbury Town, coming onto the pitch as a 36th-minute substitute only to be taken off after 63 minutes; he said this was typical bizarre management from Alan Buckley, who made players come to Blundell Park for sprint training on days after games.[6]
Port Vale
He joined Port Vale on a free transfer in January 2008.[21] He made 13 appearances in the 2007–08 season as the "Valiants" were relegated out of League One; he scored a free kick on the last day of the season in a 1–1 draw at Southend United.[22] His stay at Vale Park was to prove a relatively short one as manager Lee Sinnott declined to offer Mulligan a longer contract.[23]
New Zealand
Mulligan signed a two-year contract with the Wellington Phoenix in July 2008.[24] However, he struggled to make an impact and made just three appearances for the club in two seasons before his contract was not renewed at the end of the 2009–10 season. He later commented, "I always had an idea of coming back to New Zealand. It was more of the lifestyle change, rather than football. There’s nothing better than playing football in the sun!"[5]
He was named part of the New Zealand squad for the 2009 FIFA Confederations Cup in June 2009.[40] He made two starting appearances at right-back in defeats to Spain and South Africa, as well as a substitute appearance in the 0–0 draw with Iraq.[41][42][43][44] Mulligan was named in New Zealand's final 23-man squad to compete at the 2010 FIFA World Cup in South Africa; he had been selected by head coach Ricki Herbert despite Herbert having released him at Wellington Phoenix.[45][46] However, he did not feature in any of the games in the tournament itself.[39]
Style of play
Mulligan was a two-footed player, able to play in midfield or at right-back.[47] He was an accomplished free kick taker.[6]