Understandably it's not feasible to extend the theory certificate expiry date for safety reasons. However, resits due to COVID-19 should be free. Learning to drive is already expensive. Government should fund free resits for anyone limited by restrictions after sitting the theory test.
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Usually learners have two years to attempt to pass the practical test but this has been significantly cut into by lockdowns and tier restrictions. This means that the expiration is not at the fault of the learner. The free tests should apply even if someone has not had their test postponed to account for the time in which the area's test centre bookings were closed, and driving tests were not taking place.