Summer Solstice Soiree was a social event held around the time of the summer solstice.
Lord Gervaisius mention it in his letter to Duma in a letter[1]. Gervaisius wore a red suit with yellow frills and brown ruffles[2] which he had asked Duma to pack specially and send to his summerhouse so that he could wear it.
It was at this event that Lord Bafford introduced Gervaisius to Carina Veloden, which started off their romance.
It is unknown who hosted the event or where.