How much notifiable non-licensed work does a worker need to do before the requirement for a medical applies?
HSE would expect employers to take a commonsense approach, so if the work was genuinely a one-off, or a very rare occurrence, then it would be disproportionate to require a medical. However, the worker would still need to take all the appropriate precautions and the employer should also be able to provide some evidence that it was a one-off.