Flowering quince (Chaenomeles) confirmed then!Have to say though that there are other species of flowering quince besides C Japonica and many hybridized varieties. I seem to think they are often referred to as C Japonica whatever their origin. I'm not 100% certain that all species/hybrids have the same tell-tale 5x seed-pockets, but 5x seed-pockets does it for me (albeit, RTCman, that 2 seed-pockets have not developed on your pictured example).
Not eatable raw even when ripe, as far as I know, but edible (quince jelly anyone?)