What does smart casual mean in this instance...?

[CakesAreNotTheAnswer]

My parents (mid 60s) have been invited for tea at the House of Lords - what does 'smart casual' mean in this instance?

For my dad - shirt and blazer no tie? Tie and shirt but no blazer?

How about my (um, voluptuous) mum? A dress? Skirt and top? Linen trousers?

It's still likely to be hot so summer themed suggestions please :)

TIA

I think smart casual for a man would be blazer, trousers, shirt and no tie. For your mum any of those would be ok as long as they are smart enough iyswim!

Or maybe a linen suit with a shirt for your dad.

I'd love to do that, OP. How did they get to be invited?

By the way, isn't there a contact number where you can ask about that sort of thing?

Oh sounds lovely! I reckon overdress rather than underdress. Then you just look like the kind of person who like to dress smartly, rather than risking looking shabby. I think linen trousers for your mum only if they are smart and tailored, otherwise a dress. Skirt and top are hard to get right (well, I find it hard!)

a family member invited them. Not sure how he did it but I can ask.

I think they were just told smart casual and are struggling with what that might mean

There will be a lot of people in formal business dress there, suits etc. and sone slightly more casual business dress. So men wouldn't look out of place in blazer no tie. For your mum I'd say avoid looking like a wedding guest but all your suggestions sound fine. They'll have a lovely tine