York Historic Environment Record

The air raid shelter is of a trench-built type that is particularly large for a domestic shelter, especially compared with the familiar Anderson shelters made of corrugated iron that were approximately six feet high, nine feet long and four and a half feet wide. (http://www.gatesheadgrid.org/westallswar/archives/cat_air_raid_shelter.html). The size of this shelter (8.1m x 1.95m) is not much smaller than communal street shelters such as those recorded in Gateshead that measured roughly thirty feet long by six feet high and six feet wide. It is unlikely that the shelter was intended as a communal shelter – its size may be explained rather by the size of the house that it originally served.
The shelter at The Mount may be distinguished from Stanton type shelters that were made of pre-fabricated concrete arch-shaped sections. The construction method of this shelter is shared by others known from elsewhere in the country. An example of a domestic shelter recorded in Charlwood, Surrey (http://www.subbrit.org.uk/sb-sites/sites/c/charlwood_air_raid_shelter/index.shtml) was of a different shape but had the same brick walls, plastered interior and thick concrete roof. The internal plastering may have been an attempt to prevent flooding since that was a common problem with sunken and semi-sunken shelters.
It seems likely that the shelter at The Mount was self-built by the householder, which was often done by wealthier households that did not qualify for the free issue of an Anderson shelter. Its likely self-built origin explains the poor quality of the mortar and the irregular internal shape of the shelter with three columns along the northeast side and only one column and a ‘dog-leg’ on the south-west side.

On-Site Archaeology, 2006, 128 The Mount (Unpublished document). SYO1109.