Re: Arrivals.- Gail's Characters Percy Weasley went in dress robes, because that's what he knows, and that's what he's most comfortable with. Basically, the robes look like a suit with a long, floor length jacket ... olive in color, because he thinks it looks good on him.
Mycroft Holmes takes 'formal wear' very seriously, and wore a tuxedo.
Stephen Strange essentially wore a dressier version of his usual clothes because that's how he rolls.
John Watson came with Sherlock, which is not surprising, but this is the first time he's coming with Sherlock not as a friend, but as a date. He's going to be low key about it, no overt public displays of affection, but they will arrive with John holding Sherlock's hand. John will wear a suit that Sherlock picked out for him.