Minor spoilers until the blue spoiler warning Edit
Mr. Peter Penrose is the school librarian at St. Thom Huell. Unlike most of the students and faculty he has figured out the secret to not getting killed within 3 years as he as been at the school for at least 20. He tends to speak in a melodic tone which often comes off as singing. In the past, he has acquired rare books on the occult for Imogen, and has often been seen going into the basement, where, according to him, many rare books are stored, but has also been a place where many strange occurrences have been observed.
While James was being in a ritual in episode 1, Mr. Penrose was observed on the scene, but did not intervene despite his authority as a member of staff. It is unsure as to whether this lack of intervention is the result of cowardice, self-preservation or ulterior motives, or a combination of the above.
In episode 4, he drove a minibus taking Barnaby and Robert to a secondary school quiz in London at the Alexandria Hotel, along with their team members as well as the team from Greater Rosewater Comprehensive. However he was not seen after he went to park the bus at the beginning of the episode.
With this information it may be concluded that Mr. Penrose possesses a pre-1997 Class B (inc. Class D1) driving license, allowing him to drive cars, cars and trailers and minibuses according to the Road Traffic Act (amended 1988), giving him a significant advantage over the student body. This does make you wonder why it took him so long to find a parking spot.
Rather curiously, Mr. Penrose has a reputation as somewhat of a shut-in, rarely venturing from the library. This poses further questions as why he volunteered or was selected to accompany the quiz team to London, as opposed to any of the other teachers.
This section contains spoilers for Layla the Vampire Slayer Season 1.
I'm serious BIG spoilers for season 1 of LtVSPen and Ink
It was recently found out that Mr. Penrose is actually the fallen one (fallen angel) Penemue known for giving humanity the ability to write on a parchment with a pen and ink, seemingly he has the ability to change ink at will. This leads to the golem from the museum attacking Layla. he also has the ability to drain the intelligence from people he touches which lead to James's current state as well as the loss of intelligence from multiple other people who are currently all on ward in the nearby hospital receiving treatment. it is currently believed that he can be vanquished using sky iron aka iron from meteorites.
In episode 12 he began a epic duel with with all of the crew as well as James and Violet this resulted resulted in Layla stabbing him in the heart multiple times as well as Violet using her crimson drain ability to drain his blood which apparently has a liquid time type substance in it known as fallen angel essence, from these wounds inflicted on him he died and his body turning to ash and blackened feathers before disappearing.
On his death, some crystalline essence was left. From his corpse Violet and Imogen recovered two books, a smaller hand-written looking one taken by Imogen, while Violet took the larger leather-bound one. Imogen also took a very fine pen.
After his death, his motivations were discovered in part by Imogen as a result of the book she obtained from his remains. Firstly, the book turned out to be a journal written by Penemue himself, although the account was incomplete. Starting with an apology, it noted that Penemue tried to change back as much as he could.
Penemue was not the most powerful of angels, part of the "third tranche" of angels. He fell from grace as a result of falling in love with a mortal, Robert, who was eventually "removed". Banished, Penemue was forced to subsist on the mortal plane, but not before he gave humanity pen and ink. For his transgressions, he was made to live with a degraded brain. He found that his brain and powers degraded significantly unless he drained the intelligence of mortals. Initially he attempted to do it on the evil or those whom he presumed nobody would care if they were drained - criminals, vagrants etc - but as centuries passed his inhibitions decreased and soon he started to drain anyone. The choice of targets may have affected his decision-making. Attempts at suppressing his hunger failed.
Eventually, Penemue was imprisoned somehow beneath the earth, but how he survived while imprisoned was note detailed. On escaping, Penemue surfaced in the Cotswolds before making his way towards Little Rosewater via the bus service. He drained the bus driver, and made his way towards STH, interested by the magic around the area making his way into the staff due to being able to forge records pre-digitization with his powers over pen and ink. Afterwards, he remained as the librarian, able to satisfy his own research, but still drained targets of opportunity.
In his full, terrible form, which was never fully glimpsed by the group on account of the speed of his death, Penemue had black, half-transparent and tattered wings. He had long, glowing silver hair that appeared to move by itself, and angelic, glittery features. Genuinely terrifying, the form would have inspired awe and fear among his opponents. However, his human guise or partial-human guise did not inspire that much fear.
Penemue was also a frequent visitor, though not the owner, of the Library of Fates Told.
Penemue is a fallen angel in Enochian lore who gave man the ability to understand writing and use ink and paper.