I have chewed over this little bag design for ages (excuse the pun) and have decided my first effort, Beagle Bag Version 1 , though it worked well and has been used a lot, was a little over the top for a simple activity.
So number two is pared down but still practical, using the same waterproof outer and ripstop inner. The top simply folds over and fastens with a magnetic snap and it has an outer zip pocket and an inner slip pocket. The strap is long enough to be worn across the body, and could be used as an emergency lead. At the side is a D ring to attach to a belt or whistle.
The way its been raining here lately, think I will make one for myself!