The Queen Elizabeth Hall, Purcell Room and Hayward Gallery on the South Bank are now closed, preparing for a two-year refurbishment, and will re-open in 2017, which is exactly 50 years since they first opened in 1967-8. They are immune from listing status, unlike the Festival Hall, which is Grade 1 and the National Theatre is Grade 2 listed.

According to legend King Charles the Second, who ruled Great Britain for twenty five years after the restoration of the monarchy in 1660, was told, when the astronomer royal Sir John Flamsteed complained about the ravens, that the safety of the kingdom was threatened if the birds ever left the Tower of London. King Charles then decreed that there should always be at least six ravens there to prevent the Tower – and the kingdom – falling down. History does not record what Flamsteed thought of this decision but he had to accept it.