The only extant altar frontal designed by Dr. Fortescue is very striking. In his 1912 paper (Fig 3, p.15) Dr. Fortescue describes it as 'white canvas with embroidered scarlet silk'. The image from the paper is below:
However, looking at the frontal it strikes anyone familiar with North European Lenten custom as a rather beautiful modern example of Lenten Array. From Ash Wednesday the brightly coloured interiors of churches were covered with Lenten Array or Lenten 'White' the idea of which was to exclude colour until the joy of the Resurrection. Examples of modern array can be seen on the beautiful blog Vitrearum's Church Art.
The frontal is now stained in several places but overall in good condition.