Tupe Rules, My store has just been taken over by another retailer, (I'm in the UK)?

The shop that I manage which is part of a chain was taken over earlier this year. My shop is now part of a refit, to reopen as the new trading proposition. I am currently the manager of the shop, however the new company have offered me a deputy managers position in another store, (on the same pay though), is this legal? I cannot see any ETO reason why they should do this. Any help greatly appreciated