Very glad that your grandfather's out of hospital! And I hope that the data-recovery hopes are realised.

Thanks.

In the absence of a radiator, perhaps something like a refrigerator would do?

No, because the chain would have to run through the handle on the refrigerator or the freezer door; there are too many chances for the mug to be pulled off the counter and smash. The nice thing about radiators is they're stationary.