The first edition of the 25inch OS maps, published in 1879, shows the area that is now an allotment garden as rural fields, labelled 'Peterswell.' However, the landscape had changed dramatically by the time the second edition of the 25inch OS maps was published in 1900. The town of Barry had expanded, with housing and schools fringing the edge of the fields shown in the 1879 map. The two fields on the north western border of this new development are now labelled 'Allotment Gardens.' The most northerly allotment garden had a perimeter of approximately 915 metres, whilst the easternmost allotment garden had a perimeter of 1,375 metres. The fourth edition of the 25inch OS maps, published in 1936, shows that Barry continued to expand and develop. The two allotment garden fields were now divided by a row of terraced houses. The northernmost allotment garden was bordered by housing on its south western and south eastern side. It had a perimeter of 950 metres. The allotment garden to the south east had been entirely surrounded by housing, and had a perimeter of 878 metres, with a reading room on its southern edge. In 2017, the OS map shows that this pattern of development had continued. The southernmost allotment gardens have disappeared entirely, whilst the northernmost allotment gardens have a perimeter of 870 metres.
Sources: modern and historic OS maps; allotment page of Vale of Glamorgan website
M. Ryder, RCAHMW, 15th August 2019