With regards to London property owned by famous people or featuring in films increasing its value, the answer is no.  I very much doubt that my buyers would be shallow enough to pay more for a property which has been owned by a famous person, other than possibly with the exception of real historic value, or been used in a major film.

If anything it may detract from the appeal, as it becomes a “marked” property which is easily recognisable. If it is of architectural or special design interest and that is why it had been featured in a film, then this would have been reflected in the price from the outset.