Highly likely ref the lift - even back in the 80s it seemed rare for passengers to be allowed to use station lifts unaccompanied I seem to recall. so they were mainly used for mail / parcels and eg a wheelchair user being pushed by a member of staff for example.Am I right in thinking that the chord(s) were mainly used for postal purposes to allow Royal Mail a link from the WCML to the North East and South West? I believe Tamworth was an important postal railway hub because of its links all over the country back in the day.
I may be wrong here as well, but I also believe that the lift on platform 4 was originally built purely for the mail to be transferred from each level quickly and easily and that is why it is so far away from any of the station buildings