Kris
The seats in the back of the 86"/88" S1 are almost identical to the ones in the S2/S2a military apart from the backrest and the brackets to the side of the cab. In fact the hinged base in the S1 version and the S2/S2a/S3 is the same part number.
The backrest is fixed to the top of the wheel-boxes with 4 bolts, washers, spring washers and nuts. There is also a bracket to fix to the side of the hard-top although for soft-top models (from memory) the backrest was fixed with a spacer, nuts, bolts etc through the side capping and seat backrest frame.
If you take the S1 1954-57 parts catalogue to the RTA, they can not require an engineers report because it is an original fitting.
If you want I can copy the book when I get home tonight and email/fax it to you.
Diana

