Penn has been on the national list of officials for 12 years, having been promoted as a football league referee in 2002.
Penn has only stood in one Millers fixture this campaign, in which Stephen Brogan broke his leg, the 1-1 draw at MK Dons earlier this season when Danny Harrison netted the equaliser. Penn's not a lucky chap for young Steve as ironically Saturday is Brogan's 20th birthday!
Penn's seasonal stats read 29 games in the middle, and a total of 61 yellows, with 6 men sent for an early bath.
His assistants at the weekend are:
SJ Ross (Lincs) and PI Thompson (Derbyshire)
N Murphy (Notts) is the fourth official.