If she felt forced to resign then the only claim she can make is for constructive dismissal. This occurs when the following two elements are present:
· Serious breach of contract by the employer; and
· An acceptance of that breach by the employee, who in turn treats the contract of employment as at an end. The employee must act in response to the breach and must not delay any action too long.
A common breach by the employer occurs when it, or its employees, have broken the implied contractual term of trust and confidence. The conduct relied on could be a single act, or a series of less serious acts over a period of time, which together could be treated as serious enough (usually culminating in the 'last straw' scenario).
Taking a photo of her is not in itself that serious but could be if it was done covertly and then used without her permission. If she knew the photo was being taken and assuming you had not used it then it is unlikely this would be that serious to justify resignation.
In any event the affected employee would initially be expected to raise a formal grievance in order to officially bring their concerns to the employer's attention and give them an opportunity to try and resolve them. If the issues are so bad that the employee can't even face raising a grievance and going through the process, or if a grievance has been raised but has been unsuccessful, then they can consider resigning straight away. Again, I do not think they were that bad to justify that.
Following the resignation, the option of pursuing a claim for constructive dismissal exists. This is only available to employees who have at least 2 years' continuous service. There is a time limit of 3 months from the date of resignation to submit a claim in the employment tribunal. However, this is a very difficult claim and to submit it she needs to pay over £1000, which she may not ever do.
So you can refuse to pay her anything by saying she had no justifiable grounds to resign and that you have no obligation to pay her anything now.
This is your basic legal position. I have more detailed advice for you in terms of the rights you have if she takes this further, which I wish to discuss so please take a second to leave a positive rating for the service so far (by selecting 3, 4 or 5 stars) and I can continue with that and answer any further questions you may have. Don’t worry, there is no extra cost and leaving a rating will not close the question and we can continue this discussion. Thank you