The oldest brakevan to become a VW was Z83 which was converted from Type 1

VW5069 was reclassified from Z83 in 1961. It was written off in 1976.

Originally built in 1910 as Z4998 this van became Z28 in 1938 and finally VW5129 in 1970. It was written off in 1976.

After 1986 when the use of brake vans on ordinary goods trains came to an end, surplus Z vans were available for conversion to workmen's vans. Written off Z548 (type 17b) was written back as a VW in 1986. Z537 was also re-classified VW but I don't know when (but probably around the same time).

Above and Left VW537. Below VW548

There was also at least one type 18 van (Z571) reclassified as a VW again I have no dates. I also only have a photo of one side.

Later conversions of Z class vans to workmen's use were not reclassified and remained as class Z.