The cheapest way would be to get a Voip number on say a London 020 exchange from www.sipgate.co.uk (looks impressive in the nation's capital etc) and the calls then arrive on your computer or at your Voip ATA call equipment wherever you want it to (even overseas if you have broadband there) for no extra charge.

You could get a Voip number on your local phone exchange from www.sipgate.co.uk but then if your director is going to take it over that may not be a good thing.

Or in due course you could get an 0301 number when they are launched by Ofcom which will be charged to callers at the 01/02 Rate and can be redirected anywhere you want but the trouble is you will be paying a fee to have the service and possibly for the total number of minutes of incoming calls a month (but probably not much and less than the 0800 service mentioned below).

Or you could be really nice to callers and get an 0800 number from www.call080.com for only £5.00 per month for 500 minutes of calls redirected to an 01/02 landline of your choice and 2p per minute incoming if you exceed that.

The Voip option is probably only a good one if you are moderately computer minded though as its a little fiddly to set up.