Yes, Big Brother really is watching.
The Motor Insurance Database is a central register of every motor insurance policy in the UK, and it cross references the DVLA records of car ownership so that police authorities and other regulatory bodies can find out almost instantaneously who owns a particular car and whether or not that car is insured by that person. To make life more interesting the database can be accessed automatically by computerised systems making use of numberplate recognition technology which means that cameras can scan traffic passing by, zero in on any vehicles which the police may have an interest in looking at and then this information can be passed on to a patrol car a little further down the road. This all means that the chance of getting away with driving a vehicle without insurance is as near to zero as makes no difference.
Officialdom is nor as efficient as it could be ....
Here you are, though, buying short term car insurance, perhaps just for one single day. You may have borrowed a car, perhaps you are test driving one that you are thinking of buying or you may be taking a vehicle which was the subject of a SORN declaration for an MOT test. Since the vehicle is covered by insurance all this is quite legal, however there is one fly in the ointment; although the MID is updated around 10,000 times per day it is often out of date by several days, particularly after a weekend. If you have taken that single day policy out only that morning it is possible that the details of the policy will not yet be recorded. Indeed, the policy could have expired before the details of it have been recorded.
Print your policy documents - just to be sure
In the event of you being asked to prove that you are insured for any reason you would have to show reasonable evidence of the fact and so it is always advisable to print off your documentation if you have access to a printer; you are given access to these as soon as the policy is issued. If you do not have a printer it would be advisable to take a copy of the link to the documentation that you have been provided with by the insurer, or save it within your mobile phone, tablet or any other Internet enabled device.
And don't forget about SORN
If you insure a vehicle that you have already made a SORN declaration on, the notification is automatically rescinded. Once the insurance is expired you are obliged to make another declaration if you do not take out another policy straightaway.