With a Pfizer special including a Pullman car that is not listed on the Six Bells Junction site

Brian Gregory gives the answer and confirms the date "On this day in 1959 I recorded 30927/29/30 at Folkestone Junction all beautifully cleaned and bearing Pfizer headboards. Three Pfizer specials ran that day taking staff on a day out to France. The trains were taken down to the Harbour Station and the three Schools were turned and serviced at Folkestone Junction in preparation for the return journey to London later in the day."