Alex Elliott was devastated when Lilly vanished in the village of Hutton Cranswick, near Driffield, 10 years ago, and assumed the family pet had been run over by a car.
But the mum-of-two - whose youngest child had not even been born when Lilly disappeared - was stunned when she was reunited with the now-15-year-old cat at a veterinary surgery in Bridlington this month.
She has now discovered that a man living just a few streets away had adopted Lilly and kept her as a house cat after thinking she was a homeless stray. The pet had been confined indoors just a few minutes' walk away while her owners thought she was dead.
Thankfully, Lilly had been microchipped and vets were able to scan her and contact Alex when the neighbour decided he no longer wanted the cat and she was passed to the RSPCA.
"At first she went missing for a couple of weeks back in 2009 and then came home - she'd always been a cat who liked to explore and I assumed she'd been locked in a shed or something. So when she went missing again soon after I didn't panic straight away. A few days passed and I put posters out and asked around the village. Eventually I thought she'd probably been knocked down by a car," said Alex, a nurse at Hull Royal Infirmary.
"I knew she wasn't coming back and I was devastated. I grieved for her, but I always wondered what had happened to her as I never had any closure."
Two weeks ago Alex received a call while at work from vets who said they had Lilly in their care and had traced her ownership records.
"The man who'd been keeping her had decided he didn't want a cat any more so the RSPCA collected her and took her to the vets. She'd been kept inside as a house cat for 10 years and he had a dog too.
"I was crying my eyes out when I saw her again - I just gave her a big cuddle. She was in good condition although her coat was coarse as if she'd not been stroked much, and I could tell she'd not had much attention.
"It's been awful for me. I should have had her with me for the past 10 years. I really want to highlight the importance of microchipping, as I would never have got her back otherwise.
"If you think a cat is a stray, don't start feeding it. Report it to the RSPCA who will take it to be scanned for a chip.
"Since she's come home she's been really loving - she loves cuddles and always did. She's gone straight back to being that cat again. She's not left my side."
Alex has four other cats and Lilly has settled in well.
"I introduced them to her slowly and they all seem to get on well. She's 15 now so she's old - I got her as rescue kitten from Cats Protection in Beverley.
"My seven-year-old daughter had only ever seen photos of her and my 10-year-old was a baby when she went missing. They adore her - they have such a loving bond."