The 'Cornish heavy cake' is also known as 'hevva cake' and was said to be named after the cry of the huer (lookout man) when he saw a shoal of pilchards. The fishermen would take this heavy cake as part of their lunch. It is like a cross between a fruit scone and a dry fruit cake.
There is an example of a 'huer's hut' on the headland at Newquay (see pic) - a small, round, whitewashed structure which the huer would use as a lookout.
Also of interest, I've included at the end, the variation called "CHIRKY WHEELER" !
Rub fat roughly into flour - do not mix too finely (i e leave fat as small pieces in the mix) as the dough needs to be a little 'flakey'. Add sugar, currants and a pinch of salt and bind together with milk. Roll out to an oblong shape. Fold one third into middle and remaining third on top again and put aside for an hour in fridge.
Remove from fridge and roll out again to about 1/2" thickness to fit the baking tray. Mark lightly with a knife into approximately 2" squares, brush with a little milk, and bake at about 190C for 20-30mins.
I found this variation in an old Women's institute book:
Prepare mixture as for Heavy Cake (with or without the sugar). Roll mixture into a thin cake and place in a frying pan. Turn as necessary, like the traditional pancake, to ensure it is thoroughly cooked through and golden brown (or slightly burnt!) on the outside.
It was aptly named Chirky Wheeler - 'chirks' is an old Cornish word for cinders from the fire. According to the old recipe book "this dish is quickly made and is satisfying to the appetite, especially of manual workers, and is more delicious than might first be imagined!"