Definitely the prize for slowest on the uptake goes to me this week.
I can't see the central column, don't understand the '4 entries must be digitally enhanced', and can't see how the answers to 22ac and 33ac slot into their clues.
No! I am "the slowest"/"Spartacus" (delete as appropriate). So the date is the introduction of decimal coinage? How does that relate the first cell of 42ac to the rest of the word : the same as in 1ac? I'm still looking for 34 and 37 dn as well.