I have been giving some more thought to the shape o my BoB/WW1 rules and the basing of my units.
Having looked at the first painted examples (armypainter soft tone works wett BTW) I have decided to rebase the infantry companies of 8 figures onto 60mm wide bases rather than in pairs on 1p coins. This reduces the frontage, allowing two units to fit side-by-side in a 15cm grid square and is simply less fiddly than the original idea. Cavalry will be mounted on similar bases in groups of 4. The bases will be 40mm deep to allow for a marker along the rear edge. I haven't decided about artillery and HMGs yet.
Rules-wise I have started to put together the sequence of play. Key to getting the feel for the period is to allow something more fluid than the volley fire of colonial warfare but not quite the flexible fire & manoevre of WW2. To this end the turn will begin with a shooting phase that will result in squares accumulating "weight of offensive fire" (WOOF) markers. The WOOFs will then play a significant role in determining how the rest of the turn flows. Units will need to take some kind of test for the effect of WOOF and markers will amso make it harder to enter a square during the movement phase. Small arms will simply roll to place a WOOF but area weapons lie artillery will place one WOOF per unit in a square to punish players who mass too much stuff in close proximity. Aircraft will also have the opportunity to place WOOF markers (I expect)
The WOOF concept is a bit of a distant relative to the blast markers of Epic:Armageddon from Games Workshop.
This all perhaps sounds a little more certain and finalised than it actually is but I think as a concept it will give a game that feels "in period".
Next step is to get some bases from warbases.co.uk and either paint up some figures or perhaps just mark the bases for now and use them as game counters.