Container: black-painted sandwich box with room for swaps.
NB: YOU NEEDN'T CROSS THE BRIDGE TO GET TO CMW7 AS THE BRIDGE IS OFTEN IMPASSABLE. GO BACK TO THE PATH AND FOLLOW IT AWAY FROM CMW5. TURN RIGHT INTO THE FIELD THEN CROSS THAT FIELD GOING RIGHT-WARDS TO CMW7.
After 'CMW3: Here Be Dragons', follow the path to the wooden footbridge. You're in the SSSI as soon as you step off that bridge. Either:
CMW4: Go straight across the field with the wood on your immediate left and the caravan park ahead of you - or -
CMW6: From the bridge end, bear LEFT and south westwards. You'll now have the bottom edge of the wood to your right. Cross the good quality, dog friendly stile and go straight across then next field.
You'll see the next stile to your right as you cross that field. What a tatty stile... it's rickety and has ribbons of electric fence running away from it on either side. Note it's position - the cache is just beyond it - but you needn't use it. Follow the electric fence leftwards to by the gate, where you can unhook it then walk the short way back to the stile. 
The SSSI comes to an end here - which is why I could lay the cache - but it runs throughout the area to the south and starts up again further west along the public footpath.
The foopath crosses the stream by the bridge and carries on to the next field - but the path to and from this bridge is always overgrown, so those in the know go through the farm gate.
Beyond the bridge, the footpath carries out across the Levels and follows a hedgerow with a stream at its foot. This hedgerow teems with wildlife and you can always hear the undergrowth rustling. The migrant birds that bring the birdwatchers to Pevensey sometimes settle in these fields in large flocks, which can be quite a sight.
I can't describe the perfection of this walk. The fields are lush, the reeds whisper in the wind, and the beauty of the Levels stretches ahead of you towards Eastbourne. Quite breathtaking.
FIRST TO FIND: LOOPYHOOP