Originally Posted by
rossmacd
So based on the above, having a ticket in U class on domestic, means that you will have lounge access
if you have an onward CE ticket on the same day. If you have a stopover in the ticket (for whatever length), then on the basis of the above, you should not have lounge access.
I'm sure someone will disagree, but having thought about this in detail, then my logic above seems logical (to me

)
From what I gather U = Club redemption which should entitle you to lounge access at your domestic point of departure no matter how long your stopover in London is.....I suspect that's why MMB states you have lounge access at all airports.
For some reason the lounge agents don't recognise this probably due to the way the domestic boarding pass scans on the computer. As you are having a stopover of +24 hours in London you won't be in possession of the CE boarding pass so you have no proof of onward travel.