Ford Escort 93 Hatchback Oil Leak

I have a Ford Escort Zetec 1.6 93/L car (96000 miles). I have noticed an oil leak that appears to be coming from the tube shown in the pictures. This is on the rear of the engine just above the drive shaft next to the oil filter. What is the tube for? Can I push it in a bit to fix the problem or is it something more serious?

http://www.hkbooks.freeserve.co.uk/carnoise/overview1.jpg
http://www.hkbooks.freeserve.co.uk/carnoise/closeup1.jpg

http://www.hkbooks.freeserve.co.uk/carnoise/overview3.jpg
http://www.hkbooks.freeserve.co.uk/carnoise/closeup3.jpg

http://www.hkbooks.freeserve.co.uk/carnoise/oil_switch.jpg

This is a better picture of the tube. If I fill the oil to the max line on the dip stick and then drive 500miles, the level will be just above the min line.

Upon inspection there is a few drops of oil on the sump to engine bolt that is directly under the switch. There is also a few drops under the sump drain bolt. The oil is also sprayed slightly over the catylic converter and some of the sub frame. I have checked the tightness of the drain plug and the sump to engine bolts.

I presume the rubber tube is the insulation for the wire to the switch contacts.