I've produced a little map with colours that have nothing to do with party politics (just order of colours in my pallette).
Red indicates the new Dulwich and Forest Hill constituency, blue is Catford, green is Greenwich and Deptford, and yellow are the bits of Bromley that are currently part of Lewisham West and Penge constituency.
In terms of party politics, both Dulwich and Forest Hill are represented by Labour MPs, Labour AM, and at ward level the new constituency breaks down as:
Labour: 14
Liberal Democrat:7
Conservative: 3
Which is roughly the same balance as the present Lewisham West and Penge constituency.
I hope the new MP will back my plan to bring the Bakerloo line underground to East Dulwich, Forest Hill, and Bell Green!