The Federation newsletter has carried many comprehensive articles on CIE (see the latest in Issue 1-11) but there have been some misleading reports in the press about the operation of this legislation.
To sum it up very briefly: vehicles must be insured if they are taxed for use on the road, otherwise they must be subject to SORN and parked on private property. The DVLA have recently released a detailed fact sheet which should answer any remaining questions. (pdf HERE)