Owen was of very short stature, and suffered from a hernia, as well as a crippled leg from a horse falling on him. Nevertheless, his work often involved breaking through thick stonework, and to minimise the likelihood of betrayal, he often worked at night and always alone. Sometimes, he built an easily discovered outer hiding place, which concealed an inner hiding place. The location of the secret room was known to only himself and the owner of the house. Examples of his work survive at Sawston Hall in Cambridgeshire, Oxburgh Hall in Norfolk, Huddington Court in Worcestershire and Coughton Court in Warwickshire. Harvington Hall in Worcestershire has seven "priest holes". Due to the ingenuity of his craftsmanship, some may still be undiscovered.