When Ricki Tarr meets Tufty Thessinger to send a cable, the ends of Tufty's tie are even. A few minutes later, the little end hangs 2 inches lower than the fat end.
When Ricki Tarr is in Lisbon, he codes the message to London and makes some calculations.
The last visible is: 1958 + 1432.
He writes in column, from right, 8+2=0 carry 1, then 5+3=8 and write 8 but there is the carry, so it is 9.
The result is then wrong.