UK based hosting provider, includes a managed hosting offering. Hat tip Steve Kemp, he works for them.
RapidSwitch are apparently one of the largest dedicated server hosts in the UK. Colocation space from £34/mth, dedicated servers from £49/mth. Build your own spec, pay for what you need. Unlimited bandwidth deals available.
United Hosting offer both UK and US based, fully managed servers. They start from £200 / $300 per month. Recommended by Henry Dillon.