Haha! That first reply made me chuckle - I can imagine some clowns saying stuff like that and thinking you'd be fooled. Even
I wouldn't be fooled!
Employer sent Character to private OH (occupational health) doctor, who then "recommended" Character see private CBT Therapist (a psychiatrist, rather than a psychologist), who is in cahoots with Employer. In a nutshell: No shrink = No return to work. Employer is doing all this to continue to gaslight Character (i.e. hoping they'll eventually believe/accept they're mad (they're not, btw)) and also as an arse-covering exercise to look all kind and caring as part of their squeaky clean front.
Big thanks!
p.s. Would love to know if Character's own NHS GP can legally override the Employer and their associated private doctor...
There are a whole load of things that I'm finding implausible about the whole scenario. Medical things, employment law things and also the motivation of the employer. Why would any employer want an employee signed off on long term sick? They're being paid, doing no work, and the employer has to get a temp to replace them or get someone else to do their job as well as their own. It's a huge pain in the arse. Doctors notes are to ensure people have job security in spite of being on long term sick. It's a legal protection for the employee. Not something an employer wants to enforce.
Employer's can't choose employee's doctors. They can't ignore sick notes (the official ones used to sign people off work) from an employee's GP.
I also think that you're taking the gaslighting thing a bit literally. Usually, gaslighting doesn't come from the intention of one person to make another think they're insane. More often it's when there's bad things going on (often bullying, but can be any bad thing that the employer wants to hide) and when the person that's being subjected to the gaslighting asks questions or makes complaints in relation to it, the employer (or whichever person is in power that's doing the gaslighting) responds by denying what's going on and implying that the person questioning/complaining about it is mistaken, being too sensitive, being paranoid, etc. It's an elaborate form of victim blaming in most cases.
It's done in subtle ways and the person doing the gaslighting may not fully realise they're doing it, i.e. they're so intent on covering up their own or colleagues shitty behaviour that they convince themselves that the person complaining really is just imagining it (paranoid, too sensitive, etc). When subjected to this kind of gaslighting for long periods, the person does start to question their own judgement, especially when it seems like the whole workforce is saying one thing and they're the only one that perceives it a different way... it often happens when there's a whole gang of bullying employees who are covering up what they're doing with victim blaming and gaslighting.
The deliberate kind of gaslighting, where person A sets out with the intention of making person B think they're going insane is different. Yes it probably does happen occasionally. A very controlling, abusive spouse/sexual partner may do this to have more control over their spouse/partner. An employer to an employee... not so much as the employee can just leave. Maybe the employer knows that the employee isn't in a financial position to find another job, but even in that case, they can control the employee when the employee's in the office, but not when they're at home, and if they're on long term sick, then effectively that employee has temporarily broken away from being controlled by them. This is probably the most important of all the reasons why your scenario seems implausible. It seems far more likely that the control freak employer wants the employee at work, and if the employee's doctor signs them off sick, they can't legally override that doctor's decision, however they might resort to telling the employee that they're a malingerer and they don't trust the doctor's opinion ("yeah you can pull the wool over your doctor but you can't pull the wool over my eyes" kind of response). Forcing them to not return to work? ... doesn't make sense.
Also, controlfreakery and gaslighting go hand in hand, and they go hand in hand with bullying. Not only does this kind of think make people think they're going mad, it can cause actual mental illness. Anxiety, depression and even PTSD in extreme cases, especially if the person has no chance to get away (e.g. they can't just go and find a new job) and they feel physically in danger from the bullying.
And if the therapist and employer are in on this together... what are they trying to achieve? The employer might be doing this because they're a total control freak, but what's in it for the therapist? Why put your entire professional reputation on the line for some control freak who's trying to convince an employee that they're insane?
The process of making someone question their judgement and sanity comes from the abuser pretending that reality is different to what it is (denying things have happened, claiming things happened that didn't, claiming things happened differently to what they did, claiming things are different to what they are (e.g. insisting that the walls are yellow and the victim is mistaken by saying they're blue... when really the walls are blue)) What is the therapist actually going to be doing in terms of gaslighting the patient?
Regarding the question of an NHS GP overriding an employer plus associated private doctor - the whole question makes no sense. The employer has no legal jurisdiction in determining if an employee's fit for work or not. If you're talking about things getting legal, the employer doesn't have a leg to stand on in this. The employee does not need a doctor's certificate to prove they are fit to return to work. No sane employer would try to prevent them from returning to work, and if they did, an employment tribunal would side with the employee and wouldn't need any doctor to prove that the employee is fit for work. The question of whether someone needs to be sectioned or signed off work rests with doctors. If employers are concerned, they can advise employees to see their doctor, or if concerned that an employee is so mentally ill they can't make rational judgements they can call the emergency services. Employers can tell you to go home if you're obviously ill at work, but this is for cases where the employee turns up in spite of having flu, because they're dedicated, then they get sent home as an act of compassion.
Apologies if this comes across as very negative... when you jam all your ideas together (with or without a hammer) it's important that they come across as plausible to the reader, especially in terms of characters having believable motivations, not just in matters of employment law and medicine. There's potential in your ideas and I hope you manage to get them all smashed together in a plausible yet exciting way.