Question: Who played as a forward for Premier League club Arsenal and began his career at Southampton F.C. Under-23s and Academy?

Context paragraphs:
Theo Walcott: Theo James Walcott (born 16 March 1989) is an English professional footballer who plays as a forward for Premier League club Arsenal and the England national team.

2016–17 Southampton F.C. season: The 2016–17 Southampton F.C. season was the club's 18th season in the Premier League and their 40th in the top division of English football.  In addition to the 2016–17 Premier League, the club also competed in the FA Cup, EFL Cup and UEFA Europa League.  The season was the club's only campaign with manager Claude Puel, who took over from Ronald Koeman on 30 June 2016.  The club finished eighth in the Premier League table, having won twelve, drawn ten and lost sixteen of their 38 matches played.  They were knocked out of the UEFA Europa League at the group stage, having won two, drawn two and lost two of their matches, and the FA Cup in the fourth round, while they finished as runners-up in the EFL Cup Final losing 3–2 to Manchester United.

2013–14 Southampton F.C. season: The 2013–14 Southampton F.C. season was the club's 15th season in the Premier League, and their 37th in the top division of English football.  Having secured their place in the Premier League the previous season following a seven-year absence from the top flight, the club progressed in their league performance and achieved their main aim of a top-ten finish.  Southampton finished eighth in the Premier League table, having won 15, drawn 11, and lost 12 of their 38 games played: their best season since 2002–03.  They also made it to the fifth round of the FA Cup and the fourth round of the League Cup.

2015–16 Southampton F.C. season: The 2015–16 Southampton F.C. season was the club's 17th season in the Premier League and their 39th in the top division of English football.  It was also the club's first season in a European competition since 2003–04.  Southampton finished the season in sixth place in the Premier League, having won 18, drawn 9 and lost 11 of their 38 matches.  This result is the highest club finish in the Premier League and the highest Premier League points total (63) in the club's history.  Aside from the league, the club was eliminated from the third round of the FA Cup, the fifth round of the League Cup, and the qualifying play-off round of the UEFA Europa League.

Vince Bartram: Vincent Lee "Vince" Bartram (born 7 August 1968) is an English former professional footballer, who played as a goalkeeper.  As a player, he notably played in the Premier League for Arsenal, where he was understudy to David Seaman throughout the majority of his time at Highbury.  He also played in the Football League for Wolverhampton Wanderers, Blackpool, Cheltenham Town, West Bromwich Albion, Bournemouth, Huddersfield Town and Gillingham.  He is of current the development goalkeeping coach at Premier League side Southampton F.C.

Watford F.C. Under-23s and Academy: Watford F.C. Under-23s and Academy is the youth setup of Watford.  The Under-23 team is effectively Watford's second-string side, but is limited to three outfield players and one goalkeeper over the age of 23 per game following the introduction of new regulations from the 2012–13 season.  They play in Premier League 2 Division 2 and also compete in the Checkatrade Trophy.  The Under-18 side is the most senior team in the Academy.

2017–18 Southampton F.C. season: The 2017–18 Southampton F.C. season is the club's 19th season in the Premier League and 41st in the top division of English football.  In addition to the Premier League, the club will also compete in the FA Cup and competed in the EFL Cup.  The season is the club's first with manager Mauricio Pellegrino, who replaced the departed Claude Puel after one season in charge on 23 June 2017.  As of 30 September 2017, Southampton are twelfth in the Premier League table having won two, drawn two and lost three of their first seven matches of the season.  They were knocked out of the EFL Cup in the second round by Wolverhampton Wanderers.

West Ham United F.C. Under-23s: West Ham United F.C. Under-23s, formerly West Ham United F.C. Under-21s is the most senior of West Ham United's youth teams.  The Under-23 team is effectively West Ham United's second-string side, but is limited to three outfield players and one goalkeeper over the age of 23 per game following the introduction of new regulations from the 2012–13 season.  They play in Premier League 2 and also compete in the Checkatrade Trophy.

Southampton F.C. Under-23s and Academy: Southampton Under-23s and Academy or Saints Under-23s and Academy is the youth organisation run by Southampton F.C. to encourage and develop young footballers in the south of England.  Renowned players including Gareth Bale, Theo Walcott, and Alan Shearer began their careers at this academy.

Chelsea F.C. Under-23s and Academy: Chelsea F.C. Under-23s are the under-23 team of Chelsea Football Club.  They play in the Premier League 2, which is the top level of reserve football in England.  They were the Champions in the 2013–14 season.  The team mainly consists of under-21 players at the club, although senior players occasionally have an appearance, for instance when they are recovering from injury.  The under-23 team is coached by Joe Edwards.

Supporting paragraphs: Southampton F.C. Under-23s and Academy Theo Walcott
Answer: Theo Walcott