Given the WeaveMcQuilt's bike was on loan to Zen in July my suggestion may be a little late.
What I'm after is tool storage - Zen sell the very useful looking tool tubes:
http://www.zenoverland.com/tools/too...-standard.html
Large,
Medium or
Small
I think the medium is probably the best bet.
However, the problem is how to mount one?
What would be useful is some brackets that allow you to attach the tube to the front engine mounts (in front of the reg/rec, above the bashplate, but also allowing for the bashplate mounts?) but without affecting the wheel.
Or, somehow on the inner side of the pannier frame, so it doesn't interfere with the pannier operation.
Anywhere else one could be fitted?
Or even better! Something like this great looking toolbox to fit Touratech pannier racks - and not interfere with ARDcase panniers!
http://www.advdesigns.com/lockingtoolbox.html