The problem is that if you make an official complaint you will have to disclose this if you want to sell your house so buyers would know about the neighbours. If your complaint isn't official (ie in you name as a neighbour) I doubt that the local authority will do anything. The police cannot really do anything either.
I'm not clear if the house is rented or not, but if it is your best plan would be to approach the letting agent or landlord.
Estranged Son and Future Granddaughter
To think that London, or anywhere else for that matter, does not belong to any one demographic