Line a loaf tin with grease proof paper (or a loaf tin line) and pre-heat your oven to 150C/300F or gas mark 2.
In a large bowl, whisk together the flour, bicarbonate soda and lemon zest.
In a separate jug or bowl, whisk together the plant milk and 3/4 of the lemon juice. Place the milk and lemon juice mix to one side and let it curdle. (You'll need to keep the rest of the lemon juice to make the icing later).
In the meantime, gently the non-dairy butter, golden syrup and caster sugar until they have made a syrup. Take off the heat and place to one side to cool slightly.
Pour the cooled syrup and the curdled milk into the dry ingredients and whisk.
Pour the batter into the cake tin and bake in the centre of the oven for 1 hour 15 minutes or until its golden brown, springy to the touch and a skewer comes out clean.
Turn the cake out of the loaf tin and peel of the grease proof paper / loaf liner.
Allow to cool before decorating.
To decorate, simply mix together the icing sugar and remaining lemon juice.
Add water until its a drizzling consistency.
Drizzle all over the loaf cake and enjoy!