In California, for instance, there is Ontrac (http://www.ontrac.com/) which covers the six Western states, offering rates 40% below larger competitors. Amazon.com started using them last year, and has been steadily increasing usage. There are similar regional consolidations centered on New York and on Texas (http://www.ontrac.com/compprofileregionalcarriers.asp).
It appears that these were built by uniting a number of smaller local services by adding a "backbone" to them, don't know on what financial terms.
London certainly has a large number of very good delivery services operating within the M25, mostly on-demand (and fairly expensive). Some of these could perhaps be consolidated similarly, and likewise in other regions.
FWIW, my first-hand experience in the UK is that none of the national carriers (not even UPS and FedEx!) is nearly as good as UPS and FedEx in America; the Royal Mail is just about as bad as the wretched US Postal Service. So there is likely a business opportunity here.