In the mid 1970s the fire service and later the ambulance service began 'choosing' which part of their job they would do as part of industrial action. This invariably meant that 999 calls were answered as usual, but paperwork and routine nonsense was not completed. The employers reluctantly accepted this weak form of IA as they could continue to carry out their sharp end function of saving lives. However in the 1980s, employers began to get tough and unless you worked 100% to your contract you would not be paid.
The London Ambulance dispute in the mids 1980s (often misrepresented as a strike) was when crews refused to use new button box technology in their cabs. They did not refuse to attend 999 calls. So after their first shout, they would not book 'available' on their mobile data units so were suspended by LAS managers upon their return to base. Many ill and injured folk were put at needless pain, discomfort and danger as various Met vans were used to scoop and run victims to hospital.
In 2013, this is what is most likely to happen if Police decided not to Police football matches as part of an industrial relations dispute. The staff involved would not be paid for the day and would be effectively locked out. Anyway, what are the chances of any Govt - let alone a Tory led coalition accepting that Police can take action? About nil I reckon