I did a recon tonight and snapped 60 photos. I think I have the next PDI competition sorted ;)
I started at Victoria station

Took a photo of a theatre

Barrie emailed me to check out a bar on Palmer Street, the Adam and Eve after reviewing it on Google Maps. I snapped this:

Around St James park station were a few bars:


Near to Birdcage walk, a possible Ripper Street 2 photo

and Bird cage walk

I have some more but you'll have to wait for the next PDI comp.
I think the Victoria/St James/Westminster area is worth considering for a walk, hopefully the photos I've included here from my brief walk through have convinced some others.
Perhaps mid-November, early evening, for the 'blue hour'. I'd recommend a weekday as there will be some people around, which adds character to the area. What weekdays work best?