Lovely terrace there. As I'm buying a grade II listed house (not in London!), though no expert I've lately been delving a fair bit into the requirements.
Conclusion: a listing generally protects the building inside and out, and potentially anything on the land (garden wall, steps, shed) from that date.
By then most places will have amassed a number of non-original bits to them. But it's a distinction that counts for little, as listed status is simply a snapshot in time. Future owners have to keep it as it then was, or make a case for change.
(Caveat emptor: if unauthorised works happen, the sins of both vendor and predecessors are visited on the next buyer.)
Easiest to get agreed, unless the space has special features: a replacement kitchen or bathroom. Hardest: erecting anything new or changing the layout. Second hardest: putting in double glazing.
Which for Jan means windows and doors get special scrutiny. I'd be intrigued to learn the procedure for council-as-landlord asking council-as-conservationist for permission to change something... But anyone concerned might want to start by contacting email@example.com / 020 7525 5403.
(Lastly, heritage issues aside, and however the planned new front doors look, best make sure they're not softwood - or soon your lock mightn't work because the flimsy framed sheet will have warped.)
Thank you for that, when I get home I will scan the leaflets of the new proposed doors and send them by e-mail to James, as my i.t. knowledge is so basic..i.e. I turn off and I turn on! I will ask him to pop them under this post...:-)