Tove is ordered to make an invitation card for Mayor Erik von Frenckell's 70th birthday, which would have been in 1957 and having done that, is ordered to make a wall painting in Helsinki City Hall, which was made in 1947, so the birthday would have been EVF's 60th.
It is the morning after Erik von Frenckell's birthday party in 1947, a limousine arrives to pick up some guests. It has license plate HUH-14. Finnish license plate with three letters and two numbers was first introduced in 1962 with HUH series dating to 1965.