If you are a small/medium size business (SMB) it is wroth watching what BT is currently doing with its FTTP programme. This is of course optical fibre (optical fiber for our USA colleagues). In a lot of the country BT plan to deliver such services in a way that will provide high capacity at lot prices. This TechWorld article gives some detail, but you may get 300 Mbps for less than £100 a month and a £1000 installation. That is a lot cheaper than current business data link offerings.
It may be worth reviewing existing contracts for phone and data links in the UK to see if your suppliers can come up with a better offering. For example do you need all of those ISDN telephone services? Can you replace them with VOIP technology over a fibre data link? You might be able to save substantial amounts of money.
I hold quite a few shares in COLT and will be watching carefully how they respond to this threat. Their "escape route" of cloud/data centre services is a highly competitive field. Maybe Interoute will be casting their acquisitive eyes in the direction of COLT? The current low COLT share price could be attractive to Interoute, given the substantial network and skilled personnel held by COLT.