Twenty-week-old Grayson easily could have become one of the tens of thousands of British babies left unvaccinated against polio. Weeks ticked by, and eventually Grayson missed the polio and diphtheria jabs he was supposed to get at eight weeks old. By that point he was officially classed by the NHS as "overdue" for vaccination; effectively, he was on his GP's naughty list. Then Lily realised there was a clinic practically on her doorstep - at a location she hadn't expected. The staff who created the clinic thought: why not use one of those vacant units to administer vaccines?