The Wildlife Sound Recording Society is also taking part, and on this page [found to be defunct as of 1 October 2018] there’s a good selection of hour-long recordings from different parts of the country. Fair play to Doug Ireland for getting up early enough to start recording at 4.30am in Minsmere, Suffolk. The webpage uses a plug-in that seems to work best with Internet Explorer.
Mark Kneebone’s recording from Westwood Marshes, also in Suffolk, is worth hearing just for the eerie booming call of the bittern. There’s also a few dawn chorus recordings on the London Sound Survey made in and around town last year, in the wildlife section.