Have a look in one of the Camping & Caravanning monthly magazines under the 'Out and About' section. All the District Associations (DA's) run by stewards use rally fields throughout the year all over the UK so once you have chosen the location you require you can then approach the land owner for further details such as their rally fees, their van limit, dates required and any other relative information you need.
But you didn't actually specify that you wanted a rally field that was non C&CC related. If this is the case then you will find it extremely difficult because the land owner needs a regular income in which a club is guaranteed the best source of income. Besides, if you want to run a rally it's not just an exemption certificate you need but also a banner or flag which the stewards or marshals have to display on site which is a legal requirement with any official rally.
Don't forget to leave a review of the campsites you have visited this year or last!
No, you're right I didn't. I should have thought out my original post more carefully. I know we've been to regular campsites that have rally fields that they use as part of their regular site at busy periods, so I'm assuming that they also hold the licence for this field. This is the kind of thing I'm after. A big separate field, with access to the regular facilities. I know we used such sites when UKCS meets used to exist.