This goes well beyond naivety into into the realms of utter stupidity.
It is every persons duty to protect their own personal possessions to the best of their ability.
Taking a £3,000 Rolex into a prison, even one with a locking box in the sell is frankly negligent. I wouldn't even take a £20 Timex into a prison, and leave my expensive watches at home when I go on holiday, I take a £5 Casio F-91W (as listed on the US Department of Homeland Security watch (pun intended) list, as used by terrorists as a bomb timer because it's cheap & accurate) away with me.
Surely Mr Morley has a bank where he could store his watch if his home isn't secure enough.
As my grab always told me, the tempter is as bad as the tempted, and taking a valuable object into a prison surely counts as temptation...