CAUTION: these rawlbolts have a thread that emerges from the wall as you tighten them up, the spare thread will need trimming off (right)
Doing this "in situ" (left) is a waste of time as you will damage the wall with your hacksaw and may not have enough clearance
thread the nut all the way onto the rawlbolt
trim the threaded rod down to leave say 1" plus the thickness needed by the bracket, run the nut off the end of the threaded rod
IF you had cut it off without the nut in place you would have difficulty getting a nut back on ;)
Fix the first bracket
The brackets normally have one hole lozenge shaped to allow for left-right "yaw" adjustment
Fix the bracket in place with JUST the "adjustable" screw AND the one furthest away from it
Tighten them almost tight
Use a sprit level to align the bracket (right)
mark the position of the remaining hole
REMOVE the bracket, drill the remaining hole
REFIT the first bracket nice and tight
NOTE! See the traces of the first holes drilled to the right... spot on into the mortar or a block in the wall where the fireplace used to be
BE PREPARED to move your brackets to the left or right to hit solid masonry!!!!
Fix the rest of the brackets
With one bracket fixed to the wall you NOW have a firm reference point for the horizontal
Use the first bracket as a place to rest your spirit level right across to #2 and left across to #3 as well (right)
Proceed accordingly as above but remember you can only adjust the positioning LEFT or RIGHT...
NOT up and down!!!!
Note the 5UKP B&Q shelf already fixed below the main shelf for the print server, Dial up and ADSL modems