Does Ed know nothing about bio security?
Yes, but in these circumstances, road safety overrides biosecurity. He got them off the road and told the owner at the first possible moment. It was Pip's decision not to tell anyone, and she knew as she was asking Ed not to tell anyone that she was in the wrong, and was gambling on getting away with it, because they didn't know about IBR at that point.
I think Ed's, "oh, I'm glad Pip owned up at last," is going to be good - Carrier, Adam, Brian, Tom, probably not Tony, all having a go at him - "What?! You knew all this time?" and just as David and Ruth agreed to cover up for Pip, it all comes out anyway, so they look like they've colluded in it all.
Not that it excuses Tom being an utter git. Anyway, surely they have an inkling at Bridge Farm about the cost of lawyers? I assume veg box profits aren't so great that all Helen's legal fees would all be cleared yet.