1.Preheat oven to 170°C/340°F. Grease 20cm x 30cm (8-inch x 12-inch) rectangular pan.
2.Rinse currants in sieve under warm water until water runs clear. Drain currants on absorbent paper; pat dry.
3.Beat butter, caster sugar, syrup and extract in small bowl with electric mixer until light and fluffy; beat in eggs, one at a time. Transfer mixture to large bowl; stir in sifted flours, milk and currants.
4.Spread mixture into pan; bake about 25 minutes.
5.Meanwhile, to make icing, sift icing sugar into small bowl; stir in butter and enough of the juice to make a thick paste.
6.Spread icing over hot slice; sprinkle with coconut. Cool slice in pan before cutting.
Store squares in an airtight container for up to 3 days.Note