The funeral on Monday of Britain’s Queen Elizabeth II will see the biggest gathering of royalty this century – perhaps ever – in London. Reigning monarchs, crown princes and royals representing tens of millions of people are expected to arrive from the Middle East and Asia, but it is members of European royal houses who had a particularly close relationship with Her Majesty, some as friends and many as relatives. So who is attending the funeral, and how are they related to Queen Elizabeth II, if at all? Here’s our guide: BelgiumKing Philippe and Queen Mathilde will be representing Belgium at t…