I am afraid that I cannot give a definitive attribution. I have done a little 'digging' to check through information that I have to hand. Like Sue, I am convinced that I've seen this pattern before - but then we have all experienced quirks of memory, and I might be confusing the facts below and producing a ficticious 'memory'.
The similarity to the Walsh Walsh pieces is superficial. One must be careful not to give something an attribution with only a small amount of information based on one common feature. After all mitre cutting in conjunction with a fine intaglio cut line has been used by a number of designers and companies in the past in the UK in particular.
I do have Eric Reynolds' book on John Walsh Walsh with me and there is nothing similar other than the well known 'leaf pattern' range that has been alluded to above, nor can I see a dish with the same form.
However, in the catalogue to the cut glass exhibition that we produced there is a piece of Webb & Corbett (item no.133) that uses a technique that shows much greater similarity to the cutting on this dish - although the vase in question has a curved fine cut line with a 'spear' or 'leaf' shaped mitre cut at each end. It has the same delicate feel as the pattern on Binggirl's dish and has been attributed to Len Green (well done Sue!). In Guttery's "From Broad-Glass to Cut Crystal" there is an illustration of an identically shaped dish (no dimensions), also by Webb & Corbett. The cutting is similar in that the lines radiate out from a star cut base, BUT they are deeper cut. The central star cut, which has less points than the dish we are discussing, is echoed fives times around the bowl bisecting two of the radiating lines each time. This bowl is a design by Irene Stevens and is, from memory, illustrated in a Studio yearbook as well. The pattern and technique used on your dish are more in line with known work by Len Green.
Whilst these observations superficially suggest that the dish is more than likely to be Webb & Corbett - pattern similar to works by 'LG', and same shape as a piece by 'IS' - sadly, the information is not conclusive. Unless we can find an illustration to pin it down, I think only handling the piece would allow me to see other characteristics that would assist in an attribution.
Not conclusive, but perhaps narrowing down the possibilities?