Weird, I wonder if there used to be a pond where your wheelie bins are now? Frogs only lay their eggs (frogspawn) in or very near water, at the very same place they were hatched themselves, but if the pond or whatever has been filled in, they will get confused, and spawn as close as they can to the spot. In any event, please dont hurt the poor thing, it is only doing what comes naturally, and spawning is a once a year thing, so as soon as it has finished it will hop away and continue doing a wonderful job of eating all the slugs and other nasties in your garden! Hope this helps.