Gather a letter and a number from this cache to find the Bonus cache.
To find this cache: The steepest bit of the trail! Hidden at the top of the only thing you could call a meaningful incline on this whole series. IMPORTANT: The cache isn't on or close-to the tracks. There is no need to climb any fences or gates or otherwise try to access the railway! Trains do use this stretch of the Ickniekd Line so take care when crossing the line. It's usually gated to protect you. You'll find the cache above ground level, tucked away. Good luck!
Caches along the Phoenix Trail:
Thame Moreton Circle - 01*, GC01-West Ender, INDUSTRIAL REVOLUTION 1 (short detour)*, GC02-Not the Ivy!, GC03-Rocky Moment?, GC04-Sleeper Cell, twixt Thame & Towersey*, GC5-Beware the Rabbit, GC06-Classic Hide, Old SideTracked - Towersley Halt*, GC7-Rest Awhile, GC08-Off Track, GC09-Yumcrete , GC10-QEF?, GC11-Tree Cover, GC12-Stand Sit Jump!, GC13-Reflective Space, GC14-Lost Signal, GC15-Blasted Thing!, GC16-Eclipse, GC17-First Class, GC18-Rooky Error, GC19-Isolated Location, GC20-Bridge Hand, Virtual Insanity*, GC21-Gated Community, GC22-Antlers, GC23-Front Door, GC24-Around the Bend, GC25-East Ender, GCB-Bonus!
*Not part of the Geolympix Cyclerama series, but you may pass close-by along the way.