I don't think that it's mandatory in all cases even for such amounts. My mother gained control of my father's assets without probate. It may be that in the long run probate is a better/safer way of sorting out the estate though. I never really understood. The only problem she had was with transferring some Vodafone shares and this remains unresolved as they initially insisted on a grant of probate, then relented and allowed for a small estates indemnity form and some other documentation, then lost the application and draft for charges so it's still in limbo.