Inspired by @trojanbores on Legion at the BM. I'd thoroughly recommend the 'Holbein at the Tudor Court' at the Queen's Gallery (Buckingham Palace). It displays the monarchy's book of Holbein's preparatory sketches, which aren't often on display due to their susceptibility to sunlight. Plus some of the oils that were generated from them, so you can see the changes he made between the true life sketches & the sometimes more flattering final portrait.
I think the Holbein is one of the reasons that we identify / are fascinated by Henry's court as they are so lifelike that we see them as real people. I actually prefer the sketches - they have immediacy of a Polaroid.
One ticket gives you entrance to the Queen's Gallery for a year. Enjoy!