A single district, the Arroyo Seco Parkway Historic District, is split between Los Angeles and other parts of the county.
Another property was once listed but has been removed.
"I couldn't bear the idea of not being able to talk, or to read for people again in the future.
But I never thought I was going to die, I knew it wasn't my time yet," says Rita, who, immaculately manicured and coiffed, is dressed in a pink dress and jacket ("Diana always said it was the best colour for me").
Every girl needs a selection of LBDs at their disposal.
Demure for work, flirty for date night and down right tiny to ensure you turn heads.
And she makes a very good red carpet companion looking sexy but elegant in a little black dress by AQ/AQ.
Jessica Grist is a dancer on The X-Factor and no doubt caught James' eye as she shimmied and shook her stuff on stage with him.
Like Sam she is at Edinburgh University, which is fast becoming a favourite for aristo students.
It was doing a reading for Dodi Al-Fayed that brought him, and Diana, to her home by helicopter on 12 August 1997, just weeks before the accident in Paris which was to kill them both - an accident which Rita claims to have foretold.
"Diana had visited several times before on her own, and we spoke regularly as friends," Rita recalls.
They were put in touch by a mutual friend in 1994, and Rita did an initial reading over the phone before they met in person.
"You couldn't pull the wool over Diana's eyes," she says with a gentle laugh.