Thanks mate. That's very kind of you. I use MS Powerpoint to create the maps. I find it very easy to manipulate lines, shapes, groups of objects, etc, using that program and I'm confident that a version of it will always be available for the foreseeable future, so the files will hopefully never become obsolete and uneditable.
Sorry, I keep forgetting to say that the grids represent 1 foot of table space when using 60-80mm frontage per battalion. The original 'Shako' rules never actually said what the ground-scale was, so I base it on four battalions' frontage per foot. I've played a lot of historical scenarios where it's impossible to fit the historical deployment for formations into the allocated space, so I find that basing scenarios on the historical formation frontage works better than working from an exact ground-scale (which is a good job, as so many maps come without a printed scale).