We are now able to show some scans of the actual booklet, and especially the Machin stamps from this issue; more have been added to the original blogpost.
Comparison of 5p from prestige books. On the left, the Walsall printing from the Footballers PSB. On the right, the Enschede printing from the Merchant Navy PSB. Of course the perforations make them easy to identify but there would have been plenty of other characteristics to look for had Enschede set the perforator in the conventional way.
ROC ~ Black Print Rooster ATM Labels - Republic of China (Taiwan) Black print Rooster ATM labels with machine code 111, from Keelung post office.