The oblongs are resistors to protect the LED and the Diode. Without seeing the rest of the diagram its hard to say, but I would expect the diode to be syncing some reverse current away from some other component elsewhere.

An example would be a relay that is operated by a transistor... When the relay releases, a reverse EMF occurs and can fry the transistor, so we use a diode backwards across it to prevent this

Either way that is a simple circuit and will cost coppers from somewhere like maplins

Neil.

Neil.