Also, 'Irish' was recorded (and presumably already written) just two days after the specific events in Northern Ireland which inspired it.
Indeed, like 'Instant Karma' and 'Ohio' before it, the whole process from initial thought through to the 45 being available in the shops seems to have happened remarkably quickly.
One thing I noticed is that it was released on the same day in the UK as 'Pink Moon', Nick Drake's last LP, and, it seems, recorded initially in the same studios (Island).