Unusual Victorian grey cased glass vase with enamel decoration

This vase really captured my attention on an excursion to Sydney yesterday.
Firstly, grey is a fairly rare colour in art glass. I have a few pieces of single layer opaque grey glass, but this one is cased, creating the first point of many differences.
It is made from two layers of cased glass, a thick outer layer of translucent grey over a thinner white opaline interior, & measures 19.5 cm tall, 5.5 cm across the cut & polished top rim, & 6.2 cm across the very unusual scalloped base.
There is hand painted enamel decoration of a peculiar figure - is it some mythological being, part human, part animal? - as well as colourful patterns, plus some touches of slightly worn gilding, & two circlets of white dots.
Getting even weirder, what about that base?! This heavy vase stands surprisingly stable on the bizarre, scalloped foot. To cap it all off, there is a marking underneath as well - AH. 4862 I
I feel it is possibly Bohemian origin, mid - late 19th century. Quality is excellent, so certainly by a top maker.