Lesson number one..... when you have one free day in London to do as you please and you have been VERY excited about visiting the Letter of Van Gogh exhition at the Royal Academy.........
....... don't go to the Portrait Gallery and get so absorped in looking at every single portrait there....forget the time............and then have no time/tire yourself out so much that you then cannot go to the exhibiton that you really wanted to see.
Lesson number two........... when planning to spend the day in London sketching with a lovely pencil case full of favourite pencils and pens............. don't leave said pencil case in your suitcase so that the only writing implement you have in your bag turns out to be a leaky old green biro.
But having said all that... I had the best time losing myself in gazing at portraits centuries old, as well as some painted within my life-time, photographic portraits and portrait sculptures.... and somehow that leaky old biro made me forget about worrying about what I was drawing and just get on with it regardless!
All in all - a day well spent!