Kevin — you speculated "I suppose the cost in Australia would have been considerably higher too." Not compared with the cost in Britain. Shipping by ocean freighter in 1930 was cheap, as the two main costs involved, labour and fuel, were both considerably lower proportionately than today.
Christine — Thanks for prompting my memory. I knew I had seen Sunbeam
, the colour of the uranium yellow version of Iridescent
somewhere, and found it in Hajdamach II, p.125. Walsh named both colours in a 1929 promotional brochure Colour in Glass
. Your butterfly blue, Kevin, was called Moonbeam
This also helps with the dating of your A4514 bowl, Kevin, as the illustrations in Colour in Glass
are of Iridescent
launch patterns, most of which slightly later in the "A" factory pattern book. So your bowl was launched in 1929. Note my correction to the pattern number.
You also asked about a designer. The simple answer is that we don't know. William G. Riley, the new MD appointed in 1927, provided the inspiration and motivation to dramatically improve the Walsh product range, and so must have been involved, as, almost certainly, was their new designer, Clyne Farquharson. However I'm confident that others, such as their shop floor glassmakers, would have been involved as well.