Found and confirmed confirmed-
SOUTH DOWNS-DUCK BOX-LS,TQ.062.124, OS Landranger Sheet 197. From Parnham post carpark follow SDW westward to a brake in established trees. From water tower go 30p S of SDW then 53p 186° to water trough. Box underneath.
SOUTH DOWNS-FISH BOX-LS,TQ.054.126, OS Landranger Sheet 197. From opposite trig pillar follow SDW westward for 70p. Box is 12p S of SDW under recumbent thorn.
SOUTH DOWNS-TANK BOX-LS,TQ.071.119, OS Landranger Sheet 197. From Parnham Post car park walk on bridle-way on approx. 130° (not SDW) to cross paths - then go 250° to object then a further 200p to a large ash with ten trunks beside track now continue towards tank for 30p & through strip of hedge to a blown over thorn. Box underneath.
Confirmed but not yet found
SUSSEX-WEST-ARUNDEL-LS,TQ.057.119, OS Landranger Sheet 197. From signpost & six bar gate at map ref. TQ.056.123. follow bridle way on 140° for 420p to short path on right into field there is a 2' ash tree with ivy 2p S of this path. box is under a 9' tall holly bush 10p N.
Confirmed as being gone so don't look for it :-)
SUSSEX-WEST-COW BOX-LS,TQ.077.126, OS Landranger Sheet 197. From Parnham Post car park grid TQ.070.125 go 700p 90° (not S.D.W) to cross-paths then go 200p 20° until you see an ash tree with five large trunks 20p below track. Box is 2p E of ash tree.
The clues to Eager Eagle below are being re-written, I'll post the new ones when I get them and have confirmed the find.
So, better news all round on the search front. Got a couple more trips still to write up and have at least 2 more letterboxing searches to write up as well. More to follow as I keep saying!