Is the glass very thick and do the garden-y bits appear on different levels - ie. some on the outside and some inside - but still all cased?
The whole thing reminds me very much of an early Peter Layton piece I have, one which the seller, who is very reputable, told me was actually made by Peter Layton himself, rather than somebody working to his designs and subsequently signed by Mr Layton.
But I can't see your image of the mark on it too well, although it could be similar to the mark on my bit.