After an hours pause in Sheffield Midland station to replenish water and have the coal in their tenders trimmed, the duo were off again. I'd intended to see them again heading uphill towards Barnsley, but as I drove out of the city, I saw a footpath alongside the murky waters of the River Don (after which DONcaster was named). Following the path, this quite wonderful urban spectacle unfolded. The Don was once notorious as the filthiest river in Britain, but thanks to environmentalists the waters are now clean enough to support fish again.