Ok, I hear what people are responding with on this thread.
I make no apologies for the fact that I was brought up in a different time.
If I had the honour of an invite to an important occasion such as this I would do all possible to dress appropriately.
If todays standards are that it is acceptable to appear in casual wear (disregarding that he,s a nice chap etc) In my eyes still demeans or shows lack of respect for the occasion.
I wonder if the invitation mentioned dress code?? (in case people needed guidance)