//It was unlikely that the police were sitting outside counting the number of people going into the church. There are a lot of residential buildings close to that particular church, and knowing how many people would have been going to the Good Friday servce there, it's more likely that someone living there reported that they had seen a lot of people going to the service, which was what triggered the visit from the police.//
And how would that help, exactly, bearing in mind that the legislation places no direct limit on the numbers allowed to attend for communal worship?
Whilst it's only a guess, it could be that the local residents don't like worshipers parking outside their houses. They may have taken the opportunity to put the boot in by calling plod who obligingly pops round and stands up by the altar to announce something totally at odds with the legislation. Only a guess, though.