Visitors with a ticket to Kew Gardens can enter the garden at no extra cost. They are welcomed with a colourful display of plants reflecting the dramatic rise in average global temperatures over time.

The Grade I listed Palm House, a 362ft long structure at Kew Gardens, is the world's oldest surviving Victorian glasshouse, dating back to 1848.

Emperor Naruhito is touring the famous botanic gardens this week as part of a state visit to Britain with his wife, Empress Masako.