Thank you very very much for your responses.
We decided to use Wrike in the end. It came down to a choice between Wrike and Asana. We needed something for tasks but also something that can be used for projects and Wrike won out by a millimetre. Comprehensive enough but also simple to create, monitor and change.
These things are not cheap but if used properly the productivity benefits are immense and we have seen that already.
Again thanks all.