MARGARET'S DAISY - BUT WHAT IS IT'S NAME?

Keen gardeners - I need your help!  This pretty tallish daisy has been growing in our garden for many years, given to me by the lovely Margaret.  Have asked so many gardeners about its name - no one has been able to help so far, but have now posed the question to the RHS Plant Finding team.  Will let you know when I receive an answer.  In the meantime, you can see it in bloom at the Cater Museum, Billericay, Essex.