If he's used to being brought in by police forces, he probably has more of an insight from them to enable him to do his job.
In this case Lancs Constabulary appear not to have wanted him in the first place despite his better equipment, acted begrudgingly when he did appear, not told him much and not know or care when he finished his search.
He's probably used to being filled in and kept well in the loop of what's going on. He probably thinks they're amateurs particularly considering they didn't search upstream of the bench because they were so convinced it was the definite entry point, and he did it later on.