[4] The building was extended at the rear, by local builder Thomas Andrews,[5] to create the assembly rooms which were designed as a double cube with an apse at the east end by James Wyatt and completed in October 1783.

[6] It bears an inscription which suggests that the temple was dedicated to the gods Neptune and Minerva on the orders of Tiberius Claudius Cogidubnus, a 1st-century king of the Regni or Regnenses tribe.

[4] Functions were also held in the assembly rooms to celebrate the Coronation of William IV and Adelaide in September 1831 and the enactment of the Reform Bill in June 1832.

[8] The Italian violinist, Niccolò Paganini, performed in the assembly rooms during his tour of Britain in 1832 and the virtuoso pianist, Franz Liszt, gave two concerts there in 1840.

[10][11][12] The ante room to the assembly rooms contains a replica of the bust of Charles I by Hubert Le Sueur, the original of which is in the Pallant House Gallery,[13] as well a cabinet containing a collection of the belongings of Vice-Admiral Sir George Murray, who served with Vice-Admiral Lord Nelson at the Battle of Copenhagen in April 1801 and went on to be Mayor of Chichester in 1815.