Question: When was the Election in which Andrew Cornwell was a member of the New South Wales Legislative Assembly held? 

Context paragraphs:
New South Wales state election, 2011: Elections to the 55th Parliament of New South Wales were held on Saturday, 26 March 2011.  The 16-year-incumbent Australian Labor Party government led by Premier Kristina Keneally was defeated in a landslide by the Liberal–National Coalition opposition led by Barry O'Farrell.  Labor suffered a two-party swing of 16.4 points, the largest against a sitting government at any level in Australia since World War II.  From 48 seats at dissolution, Labor was knocked down to 20 seats—the worst defeat of a sitting government in New South Wales history, and one of the worst of a state government in Australia since federation.  The Coalition picked up 34 seats to win a strong majority, with 69 seats.  It is only the third time since 1941 that a NSW Labor government has been defeated.

Robertson ministry (1885–86): The fifth Robertson ministry was the 22nd ministry of the Colony of New South Wales, and was led by the Premier, the Honourable Sir John Robertson KCMG.  It was the fifth and final occasion that Robertson was Premier.  Robertson was elected in the first free elections for the New South Wales Legislative Assembly held in March 1856.

Robertson ministry (1877): The fourth Robertson ministry was the seventeenth ministry of the Colony of New South Wales, and was led by the Honourable John Robertson.  It was the fourth of five occasions that Robertson led the Government.  Robertson was elected in the first free elections for the New South Wales Legislative Assembly held in March 1856.

Andrew Cornwell: Andrew Stuart Cornwell (born 29 December 1969) is a former Australian politician.  He was a member of the New South Wales Legislative Assembly from the 2011 election until 2014, representing the electorate of Charlestown.  He was elected as a Liberal Party of Australia candidate, and represented that party until 6 August 2014, when he moved to the parliamentary crossbench and sat as an independent after the Independent Commission Against Corruption heard evidence that Cornwell may have breached electoral funding laws.  After earlier announcing that would not contest his seat at the next state election, on 12 August 2014 Cornwell resigned from parliament with immediate effect triggering the 2014 Charlestown by-election.

New South Wales Legislative Assembly: The New South Wales Legislative Assembly is the lower of the two houses of the Parliament of New South Wales, an Australian state.  The upper house is the New South Wales Legislative Council.  Both the Assembly and Council sit at Parliament House in the state capital, Sydney.  The Assembly is presided over by the Speaker of the Legislative Assembly.

Robertson ministry (1875–77): The third Robertson ministry was the fifteenth ministry of the Colony of New South Wales, and was led by the Honourable John Robertson.  It was the third of five occasions that Robertson was Premier.  Robertson was elected in the first free elections for the New South Wales Legislative Assembly held in March 1856.

Charlestown state by-election, 2014: A by-election for the seat of Charlestown in the New South Wales Legislative Assembly was held on 25 October 2014.  The by-election was triggered by the resignation of Liberal-turned-independent MP Andrew Cornwell, who won the seat at the 2011 election with a 43.8 percent primary and 59.9 percent two-party vote.

Forster ministry: The Forster ministry was the fifth ministry of the Colony of New South Wales, and was led by the Honourable William Forster.  Forster was elected in the first free elections for the New South Wales Legislative Assembly held in March 1856.  He was asked to form Government after the second Cowper ministry lost an educational bill in the Assembly.

New South Wales state election, 2019: The next New South Wales state election is scheduled to be held on Saturday 23 March 2019 to elect the 58th Parliament of New South Wales, including all 93 seats in the New South Wales Legislative Assembly and 21 of the 42 seats in the New South Wales Legislative Council.  The eight-year two-term incumbent Liberal/National Coalition government, currently led by Premier Gladys Berejiklian, will attempt to win a third four-year term and will be challenged by the Labor opposition, currently led by Opposition Leader Luke Foley.

Parker ministry: The Parker ministry was the third ministry of the Colony of New South Wales, and was led by the Honourable Henry Parker.  Parker was elected in the first free elections for the New South Wales Legislative Assembly held in March 1856 and, following the failure of the Donaldson and Cowper Governments to maintain the confidence of the Assembly, was asked to form Government.

Supporting paragraphs: Andrew Cornwell New South Wales state election, 2011
Answer: Saturday, 26 March 2011