I work in city of London a few days a week at the minute and I charge full whack, extras, and I'm clearing 3-4k when I leave. Sometimes closer to 5. I can't tell anyone how to do their job but there is a lot of research and personal investment that goes into this job. Any money I made I used to invest in my appearance, outfits, accomodation. Never had a day this year in London where I'm not making less than 1k. Personal investment and research is key to thrive in Central London.
But I have seen a huge decline in regular custom in smaller places like York, Leeds etc. The money is just not there and they expect very low standards (the customers). But I still made money no less than 2/3 clients on a bad day. Never lost money. All I can say is personal investment with your earnings is key.