Art restorer Amy Griffin, from the Simon Gillespie Conservation Studio, says that it should be possible to remove the graffiti without damaging the original painting.
More top news
Four men have been jailed for their part in the murder of a legal administrator, who was stabbed outside a pub on Borough High Street.
An American man has been sentenced to life in prison after travelling to the UK in a bid to murder a woman he met through online gaming.
The National Lottery has revealed the place where people win more big payouts than anywhere else - and it's in the capital