Restrictive covenants - my neighbour says they no longer apply

My neighbour and I have identical restrictive covenants imposed by the builder when the plots were developed. As far as I know all my neighbours have the same on their registers

My neighbour is planning on breaching one of the covenants and insists that as they are so old (1960s) and the original builder no longer exists, that he's not bound by them - is that true?

Restrictive covenants usually occur when somebody selling land wishes to restrict what the purchaser can do with the land. The burden of the contract (in other words, the obligation to comply with the covenants) binds the land regardless of how often the land changes hands or how obsolete the covenants seem to be.
This means that such covenants don't simply disappear or become obsolete as they bind the land for the benefit of other land and not the original seller/buyer for example.
The key to identifying the benefiting land is the covenanting clause, the preamble before the covenants are listed. For example "For the benefit and protection of the Retained land owned by XYZ Builders Limited......". This will invariably mean that on a development of say 40 plots each plot is bound by the covenants for the benefit of the other 39 plots as they comprise the 'retained land'
Of course enforcing any breach can be a tricky business and we would always recommend seeking legal advice if you/your neighbour are in dispute or disagreement.
We can supply the registered information but we can't advise you on the legal interpretation, what to do if there's a breach and more