I can confirm that it is indeed being requested on a voluntary basis and, if there is sufficient interest, a reward by way of a "subject to space being available" staff travel award as "payment in kind" may be offered. At the moment, there is no hard and fast proposal out there - management want to gauge the reaction first.
Remember: A volunteer is worth ten pressed men!
For my own part, I couldn't afford to work for a week for nothing during the normal course of events, but I possibly could put in 37.5 hours of overtime without pay if I could take Mrs Bealine away somewhere nice for an additional break in the dreary winter months!