I think this is some sort of warning lighthouse type boat from the little tower that sits on top of it. The Thames can sometimes be a very foggy place and I assume this bold red ship sets out when that is the situation to help guide the traffic on the river and while it is not needed it is kept safely here in this basin dock waiting for it moment to perform
I like the red against the monochrome background. Excellent photo!
The reflection in the water adds depth and interest to the picture… and the red boat is a great contrast.
I like how the red color is contrast from the grey.