Damage to the top of the hiding place gave me a quick clue for this one, even though my GPSr was misbehaving. TFTC.
Dan Q found GC91BEK TUBE SideTracked – Ravenscourt Park
This checkin to GC91BEK TUBE SideTracked - Ravenscourt Park reflects a geocaching.com log entry. See more of Dan's cache logs.