As a British native who began his career in the UK and later moved to San Francisco, I can tell you that the going rates for developers (can't really speak about designers) is a lot lower in the UK than in the US.
It's part of the reason I moved here.
Switching to salary-paid positions for a moment (as they might be easier to compare to your own compensation), £28k (~US$44k) seems to be a going rate for a mid-level developer and £40k (~US$62.5k) for a senior developer in London right now. Ignore financial services-based engineering positions, although there are a lot less of those today.
Current equivalent in SF right now could be $75-$90k for a mid-level developer and $100-$150k for a senior developer (or more).
Keep in mind London is a more expensive city to live in than even SF, taxes are higher (yes even compared to CA+Fed), health insurance isn't included (ok, we have socialized medicine but my point is that's part of your comp here in US), sales tax in UK is 20%, and unlike the US you have to pay property tax (council tax) on the property you live in regardless of whether you rent or own it.
Living in the UK, especially London, is incredibly expensive and I sometimes wonder how I managed frankly :P
EDIT: Oh and the reason I think wages and rates are low is because software engineering isn't a primary industry in London and a great deal of developers end up working for marketing agencies etc where they are simply "code monkeys". The BBC is another big employer (my former employer) but they only pay non-commercial wages as they are a public-service and it (used to be) seen as prestigious to work there.
Under the current economic climate, many graduates don't even find grad-level work and end up taking under-employment - the competition for the grad jobs that are out there is driving down salaries.
I also know people who 10 years after graduating are still not making £35k, although that's not specifically in the field of computer science.
It's part of the reason I moved here.
Switching to salary-paid positions for a moment (as they might be easier to compare to your own compensation), £28k (~US$44k) seems to be a going rate for a mid-level developer and £40k (~US$62.5k) for a senior developer in London right now. Ignore financial services-based engineering positions, although there are a lot less of those today.
Current equivalent in SF right now could be $75-$90k for a mid-level developer and $100-$150k for a senior developer (or more).
Keep in mind London is a more expensive city to live in than even SF, taxes are higher (yes even compared to CA+Fed), health insurance isn't included (ok, we have socialized medicine but my point is that's part of your comp here in US), sales tax in UK is 20%, and unlike the US you have to pay property tax (council tax) on the property you live in regardless of whether you rent or own it.
Living in the UK, especially London, is incredibly expensive and I sometimes wonder how I managed frankly :P
EDIT: Oh and the reason I think wages and rates are low is because software engineering isn't a primary industry in London and a great deal of developers end up working for marketing agencies etc where they are simply "code monkeys". The BBC is another big employer (my former employer) but they only pay non-commercial wages as they are a public-service and it (used to be) seen as prestigious to work there.