There was a mattress there yesterday.
I realise that there is a 3 item limit (per booking) for Lewisham's collections, and understand your point on that totally. But at the same time it may be authorised in some informal way, for a local landlord to leave stuff there when clearing out flats (most thinks look like a home clearance).
I notice it isn't always Lewisham vehicles clearing it away, hence mentioning it.
For people living in flats etc, there is no logical place to leave large items, so this would serve as a substitute.
Rightly or wrongly so, it is a complete eyesore, and needs addressing for sure, but it still worth exploring all the avenues formally before rejecting them.