Thirsk seems to be single staffed most of the time, but there's several people who work there, just not at once. The only time you see more than one person there is usually when there's about to be a change of shift. So if somebody needs to use the barrow crossing or the station needs gritting, there's no ticket office. When there is the ticket office only has one position anyway. Although there's now a card only TVM to supplement this.
What's the arrangement at Carnforth? My brother said the ticket office is only open during weekday mornings, perhaps that's a better candidate?