Cardiff gardens declared smallest in the world!

A recent story in the newspaper got me thinking (which is somewhat hard, and always dangerous) although not about the subject of the story but about the size of gardens...

It was reported that a pet tortoise made it as far as 2.9 kilometres away from home in the eight months since going missing - an average of 12 metres a day.

Horace the Herman tortoise was spotted in the middle of a road on the outskirts
of Cardiff by animal welfare inspector Nic de Calis, who then scanned his
microchip and duly returned him to his thrilled owners.
"They were so surprised to receive my call and are delighted that they will be reunited with their long-lost pet," Mr Calis said.
The owner received Horace as a Christmas present about seven years ago. He had been put into the garden - and five minutes later had vanished.?

Given that Horace's average speed was 12 metres a day, in the five minutes it took for him to "...vanish from the garden" he would have travelled 4 centimetres!!! How big was their garden, or how poor was their eyesight?