Just added a review of the original Sintra, from Hi-Fi Choice, January 1991, which you can find here. The Sintra has always been one of Royd’s top end 7ltr stand mount models and has a strong reputation for being one of his best. Its rarity only compounds this.
It may not have escaped your notice, that the rare 
is currently on right now. Well worth checking out, as this models pops only once in a blue moon.