I feel the R of 4 might be about right.
I understand the cycle time is thought to be around 5 days - that seems the settled thought.
As I've set out previously an R of 4 (as set out in the piece I think you referred to earlier), a cycle time of 5 days, would mean from just 1 person, we would have had circa 1/3 of the population infected prior to lockdown.

I don't "know" as such. All I see is assertions that don't stack up.

An R of 4 (backed up by the speed and depth a processing plant can be gone through) just doesn't sit alongside a 5% level of infection in the population.

So something is wrong.