My beloved Mr P has just said "by the way, in case you might be wondering why we're late going out tomorrow, it's because the florist said she might not be able to deliver until 12.30" 
Yes, we do always got out on Saturday lunchtime, (in fact, apart from food shopping, it's the only time we go out!) to meet up with friends in the pub.
However, as the first race isn't until around 1.50, I wouldn't have been expecting to leave the house until about 1pm anyway!
When I challenged him on this, he said that he didn't want me wondering why he was "hanging about".
I did point out that he could have been actively engaged on applying another coat of paint to the kitchen door, in which case I wouldn't have given a second thought to the time we went out, but I rather think it was too late! 
Well, I suppose at least it gives me time to wash a vase!