We are very grateful to Mark Jensen for alerting us to a brief interview with John which appears on the website of Rules Restaurant, one of John's favourite London haunts.
It was evidently carried out just before the Oscars in 1991, as John's nomination for Dances with Wolves is mentioned. JB is featured from approx. 4m 55s to 6m 35s.
Update April 15, 2015: Link no longer works.