What would you expect to find in a supply teacher’s working wardrobe? For Patricia Hartshorne, the essentials include a fine collection of fishnet stockings, suspender belts, slinky evening wear and a gleaming blonde wig. Not to mention a distinctly mannish jacket and hat.

But then teaching is, literally, her day job. By night, Patricia is an actress and singer who stars in her own one-woman shows, and whose most famous alter ego is the iconic German performer Marlene Dietrich.

“I totally become her hair, voice, everything. Even one of my sons, who came to see it at the age of 22, said to me, ‘Mum, that’s really spooky’,” says Patricia.

Marlene has taken Patricia as far afield as California and Ireland, to huge fringe festivals including Edinburgh and Brighton, and to smaller arts venues up and down the land. And in her quest to make Marlene as authentic as she can, Patricia has been granted unusual access to the star’s private belongings.

“I went to Berlin and read the letters of Marlene Dietrich and Jean Gabin, who was probably the only man she ever really loved. They were very passionate letters in French fortunately French, not German, which would have been harder to read.”

Such painstaking research has sparked rave reviews for the show, yet it was almost by accident that Patricia became Marlene. “She started as part of a show I was doing which was cabaret with a lot of comedy. I did a French tart, Carmen Miranda, an Irish nun and a couple of Marlene songs.

“I took it to Edinburgh in 2003 and one day there was an elderly actor in the audience. He came up to me and said: ‘My dear, I enjoyed your show, but I think your Marlene Dietrich needs to be developed’.

“I left Edinburgh determined we were going to write a whole show about her. There is enough in my appearance for me to be able to appear as her and fortunately I am slim enough to be able to be the younger Marlene. And I’ve got a very good wig and a fine collection of stockings and suspenders.”

Patricia, who prefers not to give her age because of showbusiness ageism, has been juggling performing and teaching ever since she left university. Juggling is probably the right word because over that period she has also been married twice, nursed elderly parents and brought up no fewer than nine children (four of her own, plus five stepchildren from her late husband).

Though she might have preferred to make her career entirely on the stage, Patricia has clearly enjoyed her years in teaching and has found her performance skills and talent for stand-up comedy have come in handy in the classroom.

“I wouldn’t say I flaunt it, but I tend to use it. An ability to project in general is a huge advantage and also to change character a little bit. I like to take the pupils by surprise.

“I find a pair of spectacles is a handy prop. I use certain larger-than-life qualities, I am told, but I am not going into Dietrich every five minutes,” she says.

A couple of years after her second husband died in 1997, Patricia returned to teaching and also to the stage with a self-penned, one-woman show that borrowed from Joyce Grenfell. She has been supply teaching English and drama close to her home in Glossop, Derbyshire, and mainly with pupils with emotional and behavioural difficulties (EBD) for which, she says, acting skills are particularly useful.

“I do become my parts,” she admits, “which can be handy when I have EBD students. One boy was mad about Elvis. He used to do Elvis songs and we used to write lots of new lyrics for them.

“Another thing he was very keen on was The Godfather I used to play the other parts, he used to play the godfather. I taught him English through Marlon Brando.

“He came in one day with a First World War poem, Wilfred Owen’s “Anthem for Doomed Youth”. ‘Read it to me’, he said. I did, looked around and he was in tears. And yet he used to tell people to eff off all the time.”

She adds: “It’s been a great job. Two of the EBD students I last spent a lot of time with got good results. One boy, who the school didn’t want to put in for English literature GCSE, got a D, which was quite something. Another lad won a Prince’s Trust award for a game he worked out with me like Monopoly but to do with drugs.”

But during the past two years, since Patricia formed the GlovesOff production company with her new partner, Michael Elphick, teaching has increasingly given way to performing and touring has become more regular.

The pair have written a new show, Alternative Medicine, which they are taking to the Edinburgh Festival, and Patricia hopes to take Marlene overseas again.

But she still has a soft spot for teaching. “I performed a preview of Alternative Medicine in Glossop and there was a boy of about 14 in the audience. I heard him say: ‘That’s Mrs Hartshorne, who is the reason I love history.’ I can’t say I won’t be bac ***

Patricia Hartshorne appears in Alternative Medicine at the Roman Eagle Lodge during the Edinburgh Festival at 4.10pm from Saturday, August 4, to Sunday, August 26 www.glovesoff.co.uk

The life and times of Marlene Dietric

*** Born Marie Magdalene Dietrich in Berlin in 1901, she was nicknamed Lena by her family and combined her two first names to make the name Marlene while still a teenager

*** After working as a chorus girl and stage actress, she made her film debut in 1923. But her international breakthrough was in The Blue Angel (1930), in which she played a cabaret singer who seduces a school teacher and in which she performed her signature song, “Falling in Love Again”.

*** She became an American citizen in 1939 and recorded a number of anti-Nazi records in German

*** Although married with a daughter, she had a string of bisexual relationships, notably with the writer Mercedes de Acosta. Among her lovers were Frank Sinatra, Yul Brynner, American journalist Ed Murrow and, according to one memoir, President John F Kennedy. But her greatest love was the French actor Jean Gabin

*** She died in Paris in 1992 and was buried in Berlin. As a fashion and music icon, she inspired singers including Madonna

*** A recording of Marlene singing “Lilli Marleen” can be found on the East Ridings’ educational history website, The World in Conflict (www.eriding.networldinconflict)