Thanks very much: very useful indeed. Maybe a couple of nights' temperatures in low single figures might toughen this patch up!
I believe this is the patch that lasted through to the new snows in 2002. That year, lasting snow arrived on the 12th October. If the same happens this year then there's a chance this one will survive if the weather is cool, although I'm guessing it'll be gone by early October. As a guide, this patch was 40m x 12m on the 28th September 2002: larger by some distance, and a week older than your measurements.
coaster, not good news not being able to see Aonach Mor. The recent warm weather has devastated the west's patches, and I'm now doubtful any of them will make it through to the first lasting snows.