We operate on our 'Christmas Hours' from after the final working day before Christmas to the first working day in January. We shut down with regards to our own internal meetings and we are happy for people to enjoy some unofficial downtime.
However, if you are under a client agreement during this time these days must be treated as regular working days. If your client also 'shuts down' during this time then we are happy for you to do the same (and you not required to use your allotted holiday) but if your client remains open then you are expected to be available to work. You are of course entitled to book these days as annual leave provided you adhere to the Holiday Policy.
Ho Ho Ho!