Changes to regs affecting Enterprise Zone Unit Trusts?

[Bazzaman]

I hold units in a number of Enterprise Zone Unit Trusts (EZUTs) originally dating dating from late 1980s thru mid to late 1990s

I was always under the impression that to avoid clawback of the original tax allowances the freehold of the property (the rump property interest) could not be sold for 25 years (although a lesser interest could be sold after 7 years).

I've recently received a notice from the managers of one of the EZUTs (which reaches the 25 year deadline in 2022) that they are on the verge of selling the rump property interest.

Did the rules change at some point? And if so how / when?