Dagmar House School, Hatfield, early 20th century
January, 2006
The booklet Hatfield & Its People - Part 8 - Schools - records the following information

The above picture is from Hatfield: A Pictorial History, and shows the Hatfield Collegiate Schools - Dagmar House (for Boys) and Alexandra House (for girls). There is a brief descriptive text which says there was a florishing cricket team, and an Old Dagmarians football team. There is also a picture of 33 girls, and three teachers, of Alexandra House taken about 1923 - and they were wearing distinctive hats.
The 1914 Kelly's Directory for Hertfordshire (online) shows John Raymond Sheehan-Dare residing at Dagmar House, North Road, Hatfield, with an entry for "Hatfield Collegiate Schools (J. R. Sheehan-Dare, principal), Dagmar House (boys) & Alexandra House (girls), North Road.
The 1901 census shows 36 boys, aged 8-16, were boarders - and there would have been more day pupils. The was no sign of an adjacent girls school, and next door was The Wrestlers public house (listed as still there in Hertfordshire Inns & Public Houses).
The records for small private school rarely survive - but it may be worth contacting HALS to see if they have anything. However their events, such as cricket matches, were more likely to appear in the local papers of the time because many of the pupils will have been day scholars of the well-to-do tradesmen, etc., in the town.
May 2007
See Hatfield Collegiate Schools - Dagmar & Alexandra Houses
There is a web page for Hatfield
If you can add to the information given above tell me.
Page updated May 2006