On the wikipedia page it says that Britain France and the United States all supported Saddam's Iraq. It just seems a little crazy to me why they would support the Iraqi invasion of Iran.
Wrt the suggestion of UK support the cited document is https://www.ft.com/content/52add2c4-30b4-11e1-9436-00144feabdc0.
My summary of that is that the UK was happy to sell arms to Iraq as long as they could be considered 'not actually weapons '. The article doesn't say this but I think it's reasonable to extend that to '...and as long as is doesn't annoy allies'. The second aspect would have precluded selling 'almost weapons ' to Iran because the USA would have been upset.
My point, such as it is, is the Brits flogging stuff to Iraq should not be taken as 'support' at a Governmental level so much as the arms trade exploiting an opportunity (distasteful though that might be) albeit with UK government being happy with the resultant income for 'uk inc'.