Hourly Rates in UK

Hope my UK-based colleagues can help out here. I'm an internal corporate resource (the only one), I guess I spend about 1/3 of my time doing forensic-type work. In these financially challenging times, I need to justify my existence not only in terms of value-add, but also bottom line sterling. So, can anyone out there give me any idea of what the going rate using external independent consulting services would be? I guess I'm looking for different rates covering different activities
* Forensic imaging (Excluding any travel and media required)
* Forensic Analysis using the likes of FTK, RegRipper et al
* eDiscovery searches and review
* Reporting

And yes, I know we need more, not less people doing this type of job internally!