Cinds 
Jen`s not going daft, I deleted my original post. 
I had realised, but it's much more amusing to think that someones just going a bit doolally.
I think that's a given on here - it aint called Ga Ga for nothing
In all honesty - if she was only due to be off for three days and the holiday had already been booked wasn't it a bit inflexible/unfair to decline the holiday request?
I think sacking is a bit harsh - employer/employee loyalty and respect should work both ways IMO.
Actually, I agree with Soozy, here.
She can't just be sacked. Verbal and written warnings have to be issued first and even if it was gross misconduct there is suspension while an investigation takes place. When she returns have a meeting with her and make sure someone is there to witness or take notes...also ask her if she wants someone present. She should never have booked anything until her holidays were ok'd. She's been very sneaky and in the process let her colleagues down. That in itself is worth a good talking to. You can let her know your suspicions but you can't accuse her outright. Hopefully it'll be the first and last time she does it.
Yes but as a supervisor she would have known the staffing situation and in my opinion should have checked whether she could have the time off before she booked a holiday.
that's what I think 
who books a holiday until you have tentatively booked the time off?
I would get advice first before doing anything. As others have said, the nature of the 'alleged' illness could come into play. It would also be interesting to see what she writes on the self cert because by signing that, she's attesting to it being the truth but if her employers can prove she was not ill (how they do that I've no idea short of following her) then, she's committed fraud by receiving sick pay despite being fit to work 
It's a problem that has being going on for decades.
To be fair, the employee did give plenty of notice that she wanted a holiday allowing the employer plenty of time to find cover. (As I see it) 
Was the other member of staff's holidays already in before the employee put hers in?
For 3 days all an employee needs is a Self Cert for illness,I doubt very very much there are grounds for dismissal ,that could and probably would lead to an unfair dismissal case....Unless it's changed greatly it is usually 3 verbal warnings and then a written which can then lead to dismissal if anything further occurs,gross misconduct used to be the only basis for instant dismissal.I doubt she can be demoted either for this,dismissal or demotion could lead to lawsuits and cost a lot of money in legal costs and damages.
It might be three working days, but it would be more than three CONSECUTIVE days ( I think you're saying) in which case she needs a self certificate if it's no more than 7 consecutive days, but will need a doctor's certificate as well/instead.
Also, what is the sick pay policy?
Thirdly, by all rights you should not book holidays before you know you can get A/L for that period. Generally spearing employment contacts specify that although you are entitled to a certain amount of annual leave (which is discretionary) it is also subject to the exigencies of the service, not on demand.
She can't just be sacked. Verbal and written warnings have to be issued first and even if it was gross misconduct there is suspension while an investigation takes place. When she returns have a meeting with her and make sure someone is there to witness or take notes...also ask her if she wants someone present. She should never have booked anything until her holidays were ok'd. She's been very sneaky and in the process let her colleagues down. That in itself is worth a good talking to. You can let her know your suspicions but you can't accuse her outright. Hopefully it'll be the first and last time she does it.
I agree with Cagney here.
The employee was wrong to presume she could take the time off in the first place, you are not always entitled to the holiday you want in certain jobs. Never book a holiday before checking you can get it off!
