I feel obliged to admit this:
As it turns out, my maths suck. I was informed yesterday that a mile is actually 64 lengths, not the 32 that I achieved... I was basing my figures on the pool being 50m in length, not 25m.
Still, I was actually happy enough to learn that, as the point of my post was less that I swam a mile and more that a definite goal is more easily achieved. I now have a new definite goal: 64 lengths. A mile!