I found this site an interesting report with some curious photographs showing a Spitfire of the RAF carrying beer kegs under the wings. I've never seen this. Can anyone tell what the purpose of it ? To see these curious and unbelievable photos, visit the link below: http://aviacaoemfloripa.blogspot.com.br/2011/01/um-armamento-curioso.html Best Regards!
This was 1944, The Spitfires were used to transport beer from the UK to Normandy once RAF airfields in France were available. It was unofficial and the powers that be turned a blind eye to it.
I can also confirm this happened, though I have no data. I suspect it was done for "health reasons" as RAF ground crews were living under canvas and potable water might have been scarce.