Sorry but this post doesn’t seem to follow on from your charge that the churches exaggerate their figures.
Where did I ever say that churches exaggerate their figures - I didn't. What I said was that when you ask people to self-report whether or not they attend church, such as in the survey you linked to in the OP, then you get a significant overestimation of attendance compared to actually measuring real bums on real pews (so to speak). I'm actually saying that the attendance reported by the churches is likely to be pretty accurate.
We see this here with CofE attendance exaggerated by about 100% in the survey compared to actually measuring attendance. Similar for RCC and this is what we see time after time when comparing self-reporting of attendance with actually measuring real attendance. So about twice as many people claim to be in church than actually are in church.
I asked you to outline an acceptable way of monitoring Church attendance. Does it involve professed Atheists with clipboards to guarantee fairness and eliminate bias.
How the CofE and RCC do this seems to be a sensible and accurate approach, which is using a census approach in all their churches at a particular time of year (usually a 'normal' set of weeks - often October and measuring numbers that attend as special festivals, typically Christmas and Easter).
Seems to work fine, provided that the organisation running the census (in this case the churches themselves) are interested in accuracy and consistency of approach (which seems to be the case). It is pretty common for all sorts of organisations to measure 'footfall' for the purposes of planning and governance.