Thanks both. I did it yesterday evening - instead of trying to line it up perfectly and push the pin through (against the spring pressure), I twisted the peg at an angle to get pin through the peg. Getting the pin through the lower part of the bracket was then simple.
No worries on the clip. I bought a box load of assorted e-clips after paying BMW £5.00 for one of the screen clips - it pinged off for no apparent reason...