I'm really enjoying the walk to get these challenges - a lovely sunny day with some great views. I thought I might have to walk on past as I had noticed some muggles about 200 metres behind me earlier. However when I arrived at the GZ I found that they had turned back. It didn't take me long to find the cache.
I'm attaching a screen shot of my Project-GC stats that show that I qualify as I have filled my "Finds by Hidden Date" grid.