It tells you in the notes.
"There is a puzzling reference in the Birmingham Gazette of 30 September 1901 (researched by Lee Gauntlett) that states Villa were wearing red jerseys "to deflect the glare of the sun." The match was against Small Heath in the Birmingham Cup but John Lerwill has confirmed that Villa did indeed wear red tops in some League matches between 1901 and 1908 while Richard Essen has found press reports that confirm they were worn untill 1911. Indeed, William McGregor frequently referred to this in his fran moss aston villa 1914-15newspaper column and expressed concern that Villa might drop their iconic claret/blue tops. It transpires that these were lightweight alternatives to the usual heavy woollen jerseys that became unbearable in hot weather. In October 2021 photographs were found by Jon Farrelly that not only confirmed these alternative tops were worn in October 1901 but also that they had short sleeves."
