why "she know" and not "she knowS" ?

[yingwen]

" The bacon had to be just as he liked it, and only she know what he liked. "
(She = Maggie Thatcher; He = her husband)

Question: Why not "only she knowS what...." ?

Thank in advance.

[engee30]

" The bacon had to be just as he liked it, and only she know what he liked. "
(She = Maggie Thatcher; He = her husband)

Question: Why not "only she knowS what...." ?

Thank in advance.

I suppose it's a typo - it should be '... and only she knew what...'