Individuals and organisations which look after war memorials are being encouraged to apply for free "SmartWater" kits.
A unique traceable liquid, which is painted onto the memorials, "SmartWater" is virtually impossible to remove - and can even withstand burning and sand blasting.
Today, the Duchess of Cornwall helped to protect the Royal Artillery Memorial on Hyde Park Corner, by applying the fluid with a paint brush.
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A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.