Bongo Fury

Hi, some advice please. Key in ignition, glow plug light on, but takes a while to go out. is it dodgy glow plugs or relay or summat else. Please help ITS FOR MY BOSS.
Cheers Folks Nibs

It's normal for the light to be on for a few seconds, whilst the plugs heat up.

Thanks but this is 30/45 seconds, mine is off after 3 so somethings not right.
cheers Nibs