Allan is a soil scientist with a particular interest in hydropedology. He has a background in soil survey, biophysical resource analysis and land evaluation and has been responsible for both systematic soil survey and land evaluation at a national level and contract soil surveys at detailed scales.

He has over 40 years experience in soil survey and soil research and has been responsible for systematic soil survey and data collection for input into the Scottish Soils Database. He has authored or contributed to over 120 technical reports and have published over 60 papers in peer reviewed science journals. A key aspect of his work is to make soils data more robust and readily accessible to other researchers for use in models. He was a key researcher in the development of the HYPRES database of soil hydrological properties for Europe and the development of the hydrological classification for UK soils (HOST) and led work to enhance and improve the national soils datasets improving these key national datasets through the provision of new data, updating and revising existing data including making new interpretations and development of web access to soil data.
He has led or been involved in assessing soil erosion risk of Scottish soils and has contributed or led various CREW projects assessing the impact of soil degradation on water quality. He was elected a Fellow of the Institute of Soil Science (F.I.Soil Sci) in 2015.