Not sure about an 850m runway, but this
Photos: ATR ATR-42-300(QC) Aircraft Pictures | Airliners.net is an Atlantic ATR42-300 doing short-field practice on Wellesbourne's 917m-long runway 18.
http://www.nats-uk.ead-it.com/aip/cu..._2_EGBW_en.pdf It works -and it's not even a 500-series ATR.
Cheers
