VivienR
Left corner front - might be Crassula arborescens but hard to tell as I don't see stems just leaves, could be a Cotyledon sp.
middle front edge - Crassula marneriana, name may have changed since my Cactus days.
right corner front - Echeveria glauca, possibly E. elegans
Can't really see the others clearly.
I should probably keep quiet on the subject.
johnw