Duke of Bedford's Family Motto



So late last night I was watching on GSN (Game Show Network) the old b&w
"To Tell the Truth" from the 50s.

A celebrity panel questions three people all claiming to be the same
person.

Last night it was three people all claiming to be the Duke of Bedford.

One was asked what the family motto was and he said "QUE SERA SERA".

All had a laugh. I thought that he could not be the real Duke having
given a Spanish motto.

Well it was he!

How did the Bedfords acquire a Spanish motto?

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