Thawed, frozen cod fillet (750 g) with skin (on the reverse side)

In order to have a juicy piece of fish after frying, I selected a fillet which was adequately thick (thin slices would dry out quickly during frying). It turned out that fillets had to be at least 750 g for them to be sufficiently thick (at least at the head end half).

After skinning (with the aid of a sharp knife), the fillet was cut into two.
The batter was a 50:50 mix of plain flour and cornflour with a pinch of baking soda and salt to taste.
Water was added to give a consistency similar to single cream.
Prior to dredging the batter, the fillet pieces were dusted with cornflour to ensure that they were dry.
Most of the batter was allowed to drip off before loading the coated fish into hot oil at 175 centigrade.
 

Crispy battered cod with and chips
 

Verdict

The fillet certainly looked like cod before after cooking viz. it was white-fleshed and came apart in wide flakes. The batter mix was crispy and light after frying.

My main disappointment was that the fish was not as fresh as it could have been because the oils in the fillet were quite strong tasting (probably due to oxidation after the long storage time taken for transport from the northern hemisphere to this part of the world, and disruption of global supply chains - much cod fish is supplied from the Ukraine). Overall, a passable imitation of the the real McCoy in London/Edinburgh
(see http://clemkuek.com/photoalbum/photo740.html).