The book, The Spy Hill story, has a bit about the Welby school district

"The school was opened in 1907 with 34 pupils in attendance. It was named Pleasant Plains School District No. 1710. The name was changed to Welby School District 1910[sic] on November 13, 1909. Mr. E.L. Little from Pilot Mound, Manitoba was the first teadcher. In 1908 a Peer's son from England came and stayed for three years. In 1924 the school burned and Mr. Doig of Birtle, Manitoba built a new one. The school closed on June 30, 1970. In the 1930s and 1940 the enrolment was from 30 to 42. In the 1950s it was from 18 to 25 and in the 1960s it dwindled away to nine in the last year."

Saskatchewan Ghost Towns has a little bit more on Welby.

"Called Pleasant Plains in 1907, Welby came into being in 1909, when the Grand Trunk Pacific Railway came through. Pleasant Plains was changed to Welby, after Grand Trunk director Rt. Hon. Lord Welby of London, England....The school closed in 1970, and by 1972, the Municipal Affairs directory listed no resident at the site.
Location: eight miles southeast of Spy Hill on the CNR line."

On a side note; it is interesting that there was also a Lilac School District 2114 SW 29-1-32-W1
and a Pleasant Plains School District 2114 near Carnduff
Carnduff being located at the legal land location of North section 35 township 2 range 33 West of the first meridian.
Welby and Carnduff are not that far from each other, when driving just 1 h 52 min (170.8 km) via SK-8 S.

It is surmised that, when the railway went through Pleasant Plain, and the name was changed to Welby, that the name "Pleasant Plain" could again then be used. Following along this way of thinking, the name Pleasant Plain could re-allocated to the Lilac School District 2114 near Carnduff resulting in two separate locations for the one room School House of the name Pleasant Plain in Saskatchewan.

A stake in the west : Carnduff and district Book Author: Carnduff & District Historical Society.
Publisher, Date: Carnduff, Sask. : Carnduff & District
Historical Society, c1979.ISBN: 0889251169

School maps used with permission