How much do London taxis cost these days?

[cupcakes]

I am going to London next week and only have a few hours to get loads of things sorted before meeting my friend for lunch. Rather than wasting time on the tube I was wondering how much taxis cost? For example, from Liverpool Street to Knightsbridge.
Or will it take ages being stuck in traffic anyway?
Any rough estimates appreciated!
TIA!

Funnily enough I'm in a black cab as I post

I think L'pool St to Knightsbridge will cost youb around #15 to #20 (no pound sign)!

Traffic will depend on time of day.

You could get tube to Marble Arch then bus to Kbridge if you wanted to speed it up.

Cab much better though, IMO.

wow! am v impressed (at your typing whilst travelling)!
What do you think Knightsbridge to Angel would be like cab fare wise? That's probably going to be my rushed bit.
Have just realised I have travel pass as part of my train ticket but may still need taxi in case of emergency. She is very old friend who I do not want to keep waiting!

Maybe a few pounds more, say 20 to 25 possibly a little less??

thank you, soapbox.