Cheaper entry to Chiswick House and Gardens on Fridays

For the next few weeks, there’s an offer on tickets to visit Chiswick House and Gardens on Fridays. Officially the offer is half price for families with children — but the offer price happens to be cheaper for adults without kids as well.
The site is worth visiting for the gardens, and while there’s a grand looking, but fairly small house to visit as well, really the gardens are the star of a visit. The main gardens are free, but you have to pay if you want to visit the wonderf