I'm told that corrosion in that connection is a well known problem and it's more likely to be that than the gearbox switch. If I could get the bloody holder out of the plug I could check the continuity. If anyone has actually succeeded in separating those two on a 6 year old Focus perhaps they could describe to me how and I'll have another go.
2001 Focus ESP 2.0. The reversing light has stopped working but the bulb filament appears fine. Looks like the bulb holder is connected to a plug but the two appear to be irreversibly joined to the point that no amount of reasonable force will get them apart. There is some sort of little plastic catch in the plug which you no doubt have to pull, press, twist, swear at, chant incantations over, annoint with the blood of a virgin, bury under a sycamore tree in the light of the full moon and dig up 6 days later, stick a small screwdriver in or otherwise firkle with to make it release the bulb holder but no easy way of seeing which of those you do. Brute force and ignorance has so far failed to adequately substitute for the correct method.