I've just completed this very same job on my 1949 end of terrace house. I used a product called NB40 or 60 I think from Strippers Paint Removers in the UK. Look them up - its excellent stuff, as is their Klingstrip for removing paint from wood, far superior to nitromors.
I brushed on the NB40, next day wet it with warm water, scrubbed hard with wire brush, connected my pressure washer to hot tap, and cleaned with warm water. Did this twice and it brought the bricks back to their original colour, and got the black paint of the pointing, though I needed to repoint anyways.