Wedgwood Jasperware 5 Colour Trophy Plate

I found this plate in a charity shop yesterday. It is Wedgwood Jasperware, but unusually and very rare, it has 5 different colours on it. I have come across Tri-colour items, but never 5 before. The colours are blue, white, lilac, yellow and green. I think it is known as a Trophy plate, and this one is dated 1977, and I think it's for Queen Elizabeth Silver Jubilee, but the other plates I have seen have it written round the centre, and on the back, but this one is plain. I am delighted to have found it, and wondering if I should go back to get the green teapot and 2 cups and saucers that were in the same shop!