Adlestrop is a small village in northeast Gloucestershire on the border of Oxfordshire. Once a stop on the A 486 railway, Edward Thomas was there on June 23, 1914 (though he wouldn't write the poem until January 8, 1915). His notebook for the day of the visit reads:
Then we stopped at Adlestrop, thro the willows cd be heard a chain of blackbirds songs at 12.45 & one thrush & no man seen, only a hiss of engine letting off steam.

Stopping outside Campden by banks of long grass willow herb & meadowsweet, extraordinary silence between the two periods of travel –
Notebook quote from