A Nightingale Sang In Berkeley Square 1979

There's a scene about 27 minutes in lasting for about 30 seconds.
In a bank at night an electrician is allegedly at work, he stops his nefarious activity when he hears footsteps coming up the stairs. Remaining concealed he sees a woman go to a vending machine, make a purchase and return downstairs. The woman is wearing a black mini-fullslip with lace at the hem, side splits and bust, with shoestring straps. We get a good close up of her lingerie once she is back downstairs.