Pwll Waun Cynon

I paid a short visit to Pwll Waun Cynon nature reserve around midday and amongst other things, was pleased to see a pair of teal and a pair of kingfishers on the river, both firsts for the year. A singing chiff chaff was also a first for the year and a welcome sound.
Butterflies abounded, particularly Small Tortoiseshell, of which I saw around a dozen, plus 4 Peacocks, 2 Brimstone and 1 comma.
While there I measured the girth of the large ash tree in the part of the reserve to the west of the railway line. I measured it just above the flare of the root buttress so as to get as true a measurement as possible and the girth (circumference) at that point is 4525mm. That's nearly fifteen feet! I have tried and failed to use the forestry commission's method of calculating a tree's age, but using the usual 2.5cm of girth per year rule of thumb, that makes it around 180 years old, which doesn't seem that much for something that size.