Certainly of great interest, Duncan. Sightings of Monarchs are very tricky. The ID should be straightforward enough as they are very distinctive butterflies but if we see one in Sussex is it genuinely wild? Birdwatchers flock to the Scilly Isles in September and October (I think mostly October) for that is when rare species are blown across the Atlantic during autumn gales. When these rare birds are blown across that is when we might expect the occasional Monarch to be blown along, with them (as they migrate down the eastern seaboard of Canada and USA). It will be interesting to see if there are any other records along the southern coast of England.  Martin K