The most reliable estimate on crime which includes unreported crime is the British Crime Survey.
Before I get the inevitable 'oh, it's HO statistics and therefore unreliable' - the fact is that the govt. very rarely fabricates statistics. The reason for this is that if they did, they'd get caught due to the presence of numerous interest groups and outside organisations. And before I get the inevitable 'ur so naive lolz', I don't say the govt. doesn't try and put a spin on things - they just don't do it through outright fabrication (it's usually through playing up 'positive' stats and playing down 'negative' ones).
Anyway, HO reports which include the findings of the BCS actually show moderate increases (and decreases in places) or what's common is no significant statistical change on the previous year. The most recent one is 2006-07 (WARNING: .pdf -
here- obviously they can't do 2007-08 yet).
Interestingly, violence by strangers seems to have remained pretty steady since the mid-90s.
That's a summary, granted, but I couldn't be bothered to slog through all gazillion volumes of the main report. If you are - they're available in lots of nice links
here