My shift has changed: ask the expert
You have mentioned that your company has had a huge restructure, but I am unaware of the size of the organisation by whom you are employed or the number of employees who had been subject to the restructure. It is also unclear as to whether there was a consultation process as part of this restructure and whether you were a part of that consultation.
It is not possible for your company simply to introduce a new shift pattern without consultation with its employees. I suspect that this has probably taken place, however, on the basis that the shift patterns have now changed. If you were not consulted when you should have been then this would be a serious matter since this might be an issue of discrimination with you being off on maternity leave. However, I suspect that you have been consulted, at least remotely, since you appear to be aware of the change in shift pattern.
The reason for mentioning these issues is that it is relevant to the reasonableness of your employer as to how the variations in your contractual terms may have been introduced. Your employer may try to argue that there was no necessity for varying terms because the contract allows for a variation in shift patterns in any event. However, if you have been working the same shift for nine years, then even if there is such a term in your contract, you could try to argue that in your case your shift pattern has stayed the same and therefore cannot be unilaterally altered come what may. Whatever the situation, however, it would be sensible for you to check your contract to see whether this is an argument that they could use.
I suggest that it is best to raise a grievance, despite the fact that you are on maternity leave and indicate that you are not happy to accept the changes in the terms on account of your personal and rather unique circumstances. The advantage of you doing it now is that you will then have more time to try to resolve it before you even returned to work. Whilst not at work at the moment therefore, when you returned it should be taken that you would be working under protest with the changed terms since you do not accept these. You should make it clear that forcing you to operate on the rolling shift arrangement would mean that not only would you have child minding issues but child caring issues. If the company was to insist on such a shift arrangement, this is such a fundamental term of the contract that you consider that maintenance of the new term would justify you making a constructive dismissal claim.
The company may try to argue that the shifts had to change for economic or other reasons. If they have a good business case for needing to do a huge restructure then it may be possible that they could argue (to counter your arguments) that the shift structure change was necessary and that it had not considered the circumstances of each individual. This argument would have more force if the majority or even all the other employees had accepted the situation. It might be worth you asking some of the other employees their views on the new shift system in order to establish the general view and whether there is largely a consensus. If there is a large acceptance of the new regime, it will make it that much tougher for you to go it alone.
An alternative to the grievance or a pre step could be to have an informal discussion about it. I would not suggest that you actually resigned and claimed constructive dismissal/discrimination, until you are sure of your facts and you have taken detailed specialist legal advice.
Laura Livingstone is an employment lawyer for Davenport Lyons in London.
Whilst every care has been taken in compiling this answer, WorkingMums cannot be held responsible for any errors or omissions. This information is not intended to be a substitute for specific legal advice.