Must admit, I haven't used Trex for ages, but do sometimes still use butter/lard or block stork/lard. Must go back to it I think! Thanks Chrissie!
Another thing I saw in a recipe a few years back for lighter pastry, especially when making sausage rolls or mince pies, was to replace 1oz in every 12 of flour with cornflour. It made my mincepies, so soft and yummy.