"Siri, Do You Ever Get Things Wrong?"

The new TV ads for Apple’s iPhone6 are built around Siri, the voice-activated program which answers verbally to questions put to it verbally.
 
In one ad, the Hollywood actor Penelope Cruz wishes to know who the prime minister of the United Kingdom was in 1868.
 
"Benjamin Disraeli," is Siri’s answer.
 
Really?
 
In 1868, UK had three prime ministers: Edward Smith-Stanley, Disraeli, and then William Gladstone.
 
When we asked Siri the same question Penelope Cruz asked, the answer we got was "Edward Geoffrey Stanley".

So, did Cruz really use Siri to get her answer?
 
Or does Siri give different people different answers at different times of the year?
 
Or is Siri all too human who can get things wrong?
 
We asked her that too, and she said "I’m sorry, I cannot answer that."