What a wonderful new polytunnel Angie and everything in perfect order (don't worry, you've plenty of time before next April when the Aussies come, to have it looking messy
)
Here, a tunnel or polytunnel means that covered place where all the rubbish gets dumpsed and the gum leaves accumulate to make a thick carpet of non-composting material which shelters slaters and beetles.
Lucky you, to have a resident frog.