The exemptions for 40 year old vehicles come into effect on 20th May 2018. My 4/4 is eligible and its "tax" and MoT are both due at the end of May, so I will let you know. Pre 1960 cars are already MoT exempt.

2021 M3W
2013 M3W - Sold
1971 4/4 2 Seater
1934 Sports