When I run a web page test for the 1st time using a client in Sydney, the 1st response is as expected, the second is MUCH faster and it fetches fewer bytes. Does this mean that the Test Client is Caching the page and then calling it back? OR, is there caching elsewhere? Is there some way of changing caching settings to avoid this so that I can get a better idea of latency?

Can you share links to the results? Normally the testing does a “first view” (cleared browser cache) and “repeat view” (closes browser, re-launches and tests again with a primed cache). If the repeat view is the second test you are referring to then that is expected (and a good thing). It helps you test to see how effectively you are leveraging the browser cache (or not).