Where according to The Husband we'll need a Chieftan tank

You may remember on Saturday afternoon, we were going to view a house that is being divided into apartments.
Photos show a fabulous old hall which looks like centre portion of Buckingham Palace. In car on way, I read details to The Husband.
"19th century country home, being re-developed into luxury flats, buyer can put own stamp on property to create unique home, lovely elevated views of the Tyne Valley, period features, secluded hideaway. Might be good thing, I say "no more mowing lawns or weeding but still garden to look at."
At entrance we drive under fancy arch bearing family coat of arms and turn up smart tree lined lane, arrive at front door, no sign of  Phyllis our estate agent. "Gosh," says The Husband, "this looks  v. swanky," just as mobile rings "We're not supposed to be at front," tell The Husband, "Phyllis says there's another entrance to side of house, just up the lane."
"Hmmmph," says The Husband as we turn into a track past two overflowing wheeley bins covered in graffiti.
"Are you sure this is right? Did you listen to the directions properly?"
It doesn't matter, it's so narrow we can't turn back any way, so we bump down waterlogged, potholed track that is over grown with brambles. The husband has tantrum about car getting dirty, rants about how the suspension  and paint work will be totally knackered. "Ridiculous," he snaps drawing up at tatty door, you'd need a Cheiftan tank to get up and down here."
"I think you can buy them on ebay,"  I say, he gives me 'that' look. We scramble over piles of building materials to reach entrance. The Husband gets cement dust on shoes and is not amused.
The agent's already inside, so we go in door that's shedding saucer size flakes of grey paint and head up the stairs that are covered in maroon nylon carpet that reminds me of student union in1978, the morning after Agricultural students Christmas party. Two light bulbs on exposed cables give off dim light on stairwell that smells like school dinners, overcooked cabbage and old cooking fat. Want to run sceaming back to car but hear Phyllis calling "Coo-eee up here," so follow The Husband as he mutters and pants all the way up four flights.
At top I am  busy resuscitating The Husband (admit am a bit smug as gym sessions with Mad Babs seem to be paying off and I can still talk) when Phyllis says "Ahh there you are." In sort of voice my mother uses when she finds my Dad in shed after he's been MIA for 5 hours.

Oh, oh, that reminds me I'm late. I'll be back later to tell you about house but have to go, as meeting Bee at gym and she's always on time for everything and gets cross if I'm late.  It' been so long since I saw her, I told her to wait under clock in entrance and wear flower in button hole. Also writing really good bit in novel about museum archives in India where professor stumbles on information about history of the cursed pearls.... Hah hah (evil laugh like villain with fluffy white cat on James Bond movies..)