In the interest of clarity, the AAIB report(1/92 - EW/C1165) states that the SMM who carried out the windscreen change had done 6 previous ones, but had not done one for two years. It insinuates that his failure to carry out basic checks to identify the "right" parts was in some way due to this previous experience. BA's procedures at Birmingham at that time allowed him to make the change without having his work checked.
The incorrect bolts in question were a mixture of wrong diameter/right length and right diameter/wrong length. Some of these had been present in the windscreen BEFORE the change.
A check on BA BAC-111s after the incident found two other aircraft with incorrect(short) bolts fitted. Two other 111s, non-BA, were found with 107 incorrect(short) bolts fitted.