According to a newsflash on egi.co.uk Slough Estates has just announced it is setting up a new serviced office on a trial basis just outside Cambridge. The units in the building will be from 350 sq ft to 5,000 sq ft, so it is not really a business centre in the Regus sense.
I think that there is a continuum between large areas of space let to a single tenant on a flexible basis, such as those managed by Trillium on the one hand and the provision of small units let to multiple tenants, as with a conventional serviced office, on the other. The new office just announced by Slough Estates in Cambridge sits somewhere between the two, as does the LandFlex buildings of Land Securities.
I expect to see many more developments of this type filling in the gaps in the flexibility continuum until there is a seamless provision of all sizes and shapes of space on flexible terms, as this is what the customers want.