Queen Mary (wife of King George V) with group at the RHS Chelsea Flower Show in 1913. The show, which was first held in the grounds of the Royal Hospital, Chelsea, in 1913, is celebrating its centenary this year. The 244 exhibitors at the inaugural event have grown to more than 500 today with 161,000 visitors now attending the show each year. Other pictures released to mark the centenary include (see below) gardeners carrying pots at the show in 1931; visitors looking at a display of cacti at the 1964 show; and, an aerial view of the show in the 1990s. The show runs from today until 25th May. For more on the RHS Chelsea Flower Show, see www.rhs.org.uk/Shows—events/RHS-Chelsea-Flower-Show/2013. PICTURES: RHS Lindley Library.