my old cat

Had a vet check? It may be a physical problem.

Otherwise...any recent changes?

No vet check as yet and no recent changes. She's in really good health generally and is otherwise behaving completely normal, i'm really confused as she's always been very clean and litter trained, or simply gone outside.

I think dlowan was indicating you should take her to the vet.

Had her there this morning, no obvious problems at all.

So what did the vet have to say about her pooing in the house?

He's taken blood for tests but thinks it's senility! :/ If that is the case I will need to find a way to 're train' her I guess.

I hope it isn't, jc sunshine!
And it mightn't be.
I've had cats live till 18+ years before having such problems. (the very oldest, 23.)
Good luck with your cat!

I hate to tell you this sunshine, but you're the one who might need to be retrained.

Jezzer, when she got old, decided she did not want to poop back where the litter box was, where it had been for years, and where she'd always shared it with one or 2 other cats (actually there were 2 large boxes back there)

She wasn't being mean, or spiteful, she was just senile.

After trying numerous things, we finally moved the litter box to where she wanted to poop, which happened to be in the middle of the dining room.

She was happy, she pooped joyfully in her new location.

Then she decided she would poop IN the box, but would PEE right outside of it, on the tile floor.
So, we went to Pet Smart and bought a big box of puppy training pads, and would put 4 of them under the box, spreading out a foot or 2 in all directions.

She was happy, she pooped in the box, and peed on her puppy pads.

There were no odors, the pads had that gel in them that absorbed very well, and locked in odors.

When people came to the house, people who'd never been here before, walked in, they would find a litter box right there. We would say "We have an old cat who's decided this is where she wants to go"
Anyone who owned a cat would simply nod their head and say "oh yeah....I know what you mean"

When Jezzer died (in my husbands arms), we moved the box back where it should be.

Buy another box, and put it wherever you see your cat poop. Let him/her decide where it should be. Put puppy training pads under it for accidents.

Thank you chai2, very insightful, i'll do whatever it takes because apart from this little problem she's such a sweetie and indeed part of the family.

Thank you msolga, I guess only time (and blood test results) will tell.