We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "The3rd Earl Of Derby"
saying something like:

http://www.bricksandbrass.co.uk/houseage/ageform.htm

I tried this again using answers(not all filled?) from a property I used to
live in some time ago which was Victorian, I knew the age of this house
because it had the date above the door in the stonework.
The site was accurate to within 4 years of its age.

That's quite neat. Similar here - an old house I had some years back
returned a date within the range I thought the house to be.
--

Dave