Just to muddy the water, there are also pics on airliners.net of it carrying the G reg as far back as 1996.
www.airlinerlist.com, which is usually pretty accurate, reckons it went onto the G register 14 Oct 1994 and has been with KLM UK since (except for the current merger, obviously).
I suppose, had it been on lease, it MAY have been re-registered and MAY have carried the original reg, but your PH-LXK MIGHT just be another aircraft too.