Player on field says head hurts, he gets taken off and assessed by doctor, if he’s ok doctor lets him back on if he isn’t he’s gone for game, they can’t do the concussion test on the field

Same ploy and blatant cheating going on here. That’s two games in a row that a prop (who has shown no sign of a head knock) has been told by the physio that he needs to come off for a concussion test, coincidently at the exact time this provides the maximum advantage to the team.
Catalanns are not doing this subtlety. The number of interchanges they use before the “concussion” one is far higher than it would be - they know full well they are going two “free” interchanges (one before before and one after after half time) or else they wouldn’t use them up so quickly in the first 30 minutes.
It’s blatant on-field cheating and needs to be called out by the other teams.

I think we need to be quite careful here, because some very serious allegations are being made against medical professionals, on the basis of nothing greater than anecdotal evidence. I didn't see the Castleford v Catalans game last week, so can't comment on what happened.

But let's look at the Remi Casty interchange last night. He clearly took a knee to the head when attempting to make a tackle and his head then hit the ground with force. It is perfectly feasible that he could have suffered a head injury in such circumstances.

He remained on the ground despite the fact that Huddersfield had an overlap to exploit. The play resulting in a drop out. This is very different to a player hitting the floor after a drop out to attempt to delay matters.

Now, let's look at the rules relating to medical staff. Here are some excerpts from the RFL's Medical Standards:

"The medical staff must use a different set of radios to the coaching staff and must operate on a wave length to which the coaching staff do not have access."

"No member of coaching staff shall use medical staff communications equipment in any circumstances."

"Match commissioners shall be entitled to check both the medical staff and coaching staff communication equipment."

Whilst these are the rules, I accept that this doesn't mean that they cannot or are not being broken. But it is not quite as simple as coaches calling out medical professionals, questioning their integrity and competence, without any substantive evidence.

I would also be surprised to see a doctor put their professional reputation and career on the line to give their employer a very minor benefit. Again, that's not to say it doesn't happen or that clubs don't pressurise doctors, but again, this is also a very serious accusation.

If coaches are concerned about Catalans alleged conduct, then I'm sure they would go down the proper channels of informing the match commissioner for investigation.

What is more likely is that players go down injured and tell the doctor that they are suffering from specific concussion symptoms, leading to their removal and during the assessment, say that the symptoms have resolved, thus gaining the benefit of a "free interchange".

I say this again with the caveat that there is no concrete evidence that I have seen to suggest that is the case. But anecdotally, it seems more plausible than a person who has worked all their life to become a doctor, to risk throwing it all away by deliberately misdiagnosing to please someone like Steve McNamara.

The general point of the post, if this is occurring, it's more likely to be the coaching staff, than the doctors.

I don’t think anyone is really questioning the medical staff. It’s obviously coming from the coaches and players.

However, don’t forget most of the time it’s a physio on the pitch not a club doctor. Often these physios are on relatively low pay and on limited term contracts, sometimes even just contracted for that specific game especially lower down the leagues you go. And we’ve seen from the bloodgate scandal that medical staff can be involved in this kind of cheating.

I agree it ultimately lays with the coaches and club officials but that’s not to say medical staff and players can’t be pressured into doing dodgy stuff.

Unfortunately, due to their actions last year with players blatantly and repeatedly faking injury, Catalans have no benefit of the doubt on this issue. They’re going to be suspected. And as they were that blatant last year and nothing was done, there’s no reason to believe they wouldn’t move on to the next step, especially as they have a big pack and there’s reduced interchanges.

Personally I think the RFL should be closely monitoring every single use of a head test interchange. Monitor the time the interchanges take place, the players involved and review match footage to see if there was any head contact.

Don't think the medical staff can be accused of anything worse than taking a precautionary approach, as indeed they're meant to. Player complains of a head knock, medics act perfectly correctly by taking them off for an assessment..

Yep. It’s very easy to fake from a players point of view.