Preheat the oven to 200C/400F/Gas 6. Grease and line a 9 inch x 12 inch Swiss roll tin Whisk the eggs and sugar in a bowl until pale and fluffy. Fold in the flour to the eggs and spoon the mixture into the tin. Bake in the oven for 7-10 minutes, or until light and springy to the touch. Remove from the oven and turn the sponge out onto another piece of greaseproof paper. For the filling, spread the strawberry jam onto the sponge and then spread with the whipped Lactofree cream, leaving a small gap around the edges. Place a row of strawberries along one edge, lengthways. Roll the sponge to cover the strawberries and repeat the process until all of the strawberries have been used. Dust with icing sugar and serve.