Are there any HHA membership offers?

Historic Houses Association'

There seems to be a 12 months for the price of 9. Has anyone used this and is it legitimate?;

caravanclub.co.uk/mem…rs/

There is also a 12 months for price of 8. The link here was from a Telegraph page from 2014 so would it still work?;

hha.org.uk/Sit…aph

I know there is a offer if with English heritage but I don't intend to join them.

TIA.