From the BBC:
A rare portrait of Queen Elizabeth I as a young princess has been discovered in a private collection at a stately home in Northamptonshire.
The portrait, dating from 1650 to 1680, was found in the Duke of Buccleuch’s collection at Boughton House.
It shows Elizabeth with siblings Edward VI and Mary I, father Henry VIII and his jester, Will Somers.
Tracy Borman said that when she was first sent a picture of the portrait she realised it had never been seen before.
“The more we found out, the more obvious it was that nobody had come across this,” she said.
“It’s clearly a copy of a lost original and it’s that mystery that we started to try to solve.
“It’s also a very different look to Elizabeth and comparing it to other portraits it helps us to solve the identity of other portraits – for example one always known as the Unknown Lady in the National Portrait Gallery.”
And here is a link at the NPG to a similar image that was previously thought to be Jane Grey, but now looks like it might be Elizabeth.