This book, which belongs to the Bodleian Library, is online here and some of you may be interested. It includes portraits of the various patrons of Tewkesbury Abbey including Robert Consul, Gilbert de Clare, Hugh Despenser the younger, Thomas Despenser, Isabelle Despenser (she actually gets two illustrations!), Richard Beauchamp, Earl of Warwick, Warwick the Kingmaker and George Clarence.
The work dates from early Tudor times and the costumes depicted reflect this, but the extensive heraldry is well worth careful study. For example on Thomas Despenser's page you will find his marital impalement with Constance of York ** and also an illustration of the short-lived impalement of Edward the Confessor's arms with the royal arms used by Richard II from circa 1397-99 as a mark of his devotion to the Saint.
**At least that's what I take it to be - the one that Thomas is more or less pointing at with his right hand. But oddly, the artist has placed Constance's arms at heraldic right (the left as we look at it) and Despenser's at heraldic left. Which is the wrong way round. Theoretically this coat represents a marriage between Edmund of Langley or Edward of York and one of Thomas's sisters! You see, you can't even trust prime manuscript sources completely.