Congratulations to Sir Nicholas for his heroic work & for still being with us to receive this honor, not to mention his humble regard for keeping his accomplishments secret.
No mention in Wiki or anywhere of when he was knighted, unless becoming Member of the O.B.E. conferred that title.
It doesn't. Being an MBE (Member of the Most Excellent Order of the British Empire) though significant, is a much lower award than a Knighthood. Nicholas Winton was made an MBE in 1983 for work he did in establishing homes for the elderly.
His Knighthood came in 2002 for his work on the Kindertransport during the Second World War. The type of Knighthood he has is what is referred to as being a 'Knight Bachelor'. It's not part of any of the Orders of Knighthood. For this reason, he still holds his MBE (if he had been made a Knight of the British Empire (KBE) it would have superseded his MBE).
The reason for making him a Knight Bachelor is because it makes it clear that he has received an Honour from the Queen twice for two different reasons, rather than (as sometimes happened) simply being initially given a lesser honour and then later being given a greater one for the same thing.
(Note, to be clear, in describing the MBE has a lesser honour, I do not want to suggest it isn't a high honour in its own right - I hold an equivalent rank in the Order of Australia (AM) and I am bloody proud of it (it's also why I've spent such a lot of time studying how this all works) - but being a 'Member' of these orders is the base rank of the Honours system - almost every other Honour ranks higher.)
I have a friend whose father was one of the rescued children. He stayed on in England for the rest of his life, and had a very successful career as a doctor which ended some years ago...yet here’s his rescuer still going strong at 105.