Here, apparently, is the first ever footage of a shark deterrent being used successfully to repel a bull shark. It does look vaguely convincing, but are there scores of outtakes we’re not being shown, in which Bernie’s leg (or those of his numerous, sadly departed predecessors) gets ripped to shreds, magic magnetic band and all? Until the co-founder featured in the video puts his bollocks where his mouth is, so to speak, lathering his testicles in bloody offal and taking the place of the test dummy amongst the ravenous bull sharks, the jury will likely remain out.