Re: "abruptly quit with immediate effect last month"
Fair enough, but bear in mind that isn't the case with all directors' contracts, and not all contractual clauses have that post-employment reach.
But clearly anyone who indulges in insider trading does on the normal understanding of the City, that lots of other people do it and get away with it*, so I will too.
* Rough numbers, 20% of takeovers are immediately preceded by an otherwise unwarranted share price increase, 70% of profit warnings are preceded by an otherwise unwarranted price dip. A suitable search will readily bring up the sources and discussion. FCA undertake about 60-80 insider trading investigations each year, but convictions run (at their highest) at low single digits per year, and in many years there's none. With around 150m trades annually on LSE (ignoring derivatives and other markets), how lucky we are that all traders are so honest and law abiding.