Hi, thanks for all the replies, I can see what you say about a small chink left between the splash panel and the sill for drainage. Poor design from MB where a 1" ID hose drains through to a piddly hole like that. Perhaps it was the plumbers day off?
Referring to a comment from Wallace W as to where the drain pipe originates, I will feed a wire down from the air scoop, with the filter out, and see if this is where it drains from. In an MB parts catalogue for this model, which I have, it shows drainage from further in. See PDF drawing attached item no 86(or# as American's do), and drain Item No 96.