Yes, as you say, maintaining an offshore wind seems to be the key to really high temperatures here, rather than the intensity of the heatwave. If I remember correctly the other time it got to 31.8C, we weren't in a particularly hot airmass, but just under high pressure with a northeasterly wind. Southamptonweather.co.uk also recorded an all time high today (since 2008), so we weren't alone (even though that station horribly overestimates sometimes!)