Dismissal of an employee due to the devastating potential consequences of that employer's actions (such as driving without insurance) may well fall within the "range of reasonable responses" and thus be fair; it is certainly not the case that where those potential circumstances did not, in fact, occur this alone renders the dismissal unfair.
Haulage Company Wincanton employed Messrs Atkinson and Marrison as drivers. They were required to have, in addition to their normal HGV licence, an ADR licence to enable them to carry dangerous loads, as required by Wincanton. Since both were over age 45 they were required to renew their licence every five years, which entailed passing a medical test.