Passage: The 1990s brought a series of 32 concerts to the Royal Albert Hall, such as the 24 Nights series of concerts that took place around January through February 1990, and February to March 1991. On 30 June 1990, Dire Straits, Clapton and Elton John made a guest appearance in the Nordoff-Robbins charity show held at Knebworth in England. On 27 August 1990, fellow blues guitarist Stevie Ray Vaughan, who was touring with Clapton, and three members of their road crew were killed in a helicopter crash between concerts. Then, on 20 March 1991, Clapton's four-year-old son, Conor, died after falling from the 53rd-floor window of his mother's friend's New York City apartment at 117 East 57th Street. Conor's funeral took place on 28 March at St Mary Magdalene's Church in Clapton's home village in Ripley, Surrey. In 1991 Clapton appeared on Richie Sambora's album, Stranger in This Town, in a song dedicated to him, called "Mr. Bluesman".  He contributed guitar and vocals to "Runaway Train", a duet with Elton John on the latter's The One album the following year.

Question: When did Conor die?
20 March 1991