I think the issue has moved on from the parties themselves however. The focus now seems to be around the perceived subsequent failure to give a straight and and honest account of events.
The Spectator has an interesting article on the art of the non-apology
‘Johnson apologises for lockdown garden party’ announced the Times on Wednesday. But did he? It’s quite a skill, the non-apology, and our Prime Minister is a non-apologiser par excellence, the Nureyev of not really meaning it. Academics working in conflict resolution have analysed what makes a...
www.spectator.co.uk
The full article is behind a paywall but the summary is:
1 Make it conditional ('I'm sorry if ...')
2 Be unclear what you're apologising for ('I believed this was a work event' - implying an error rather than deliberate rule-breaking)
3 If you have a fault, it's that you're too nice ('With hindsight I should have sent everyone back inside and found some other way to thank them')
4 The passive voice ('mistakes were made' - by whom?)
5 'I'd like to apologise' (but I'm not going to - subtle!)
6 Is there anything to apologise for anyway? ('even if the events technically fall within the guidance not everyone sees it that way')