My first suprise was seeing the price of a new one...£125 plus !
My next plan was to have a look at second hand ones and although there seemed to be some decent ones for sale they still seemed to be going for between £40 - £60 with no guarantees as to how well they had been looked after. Fortuanately for me I then noticed an auction that was finishing shortly for a "working" tilley lamp. I contacted the seller and asked if the Bowl, Glass, Hood etc were all ok (the expensive bits) and was told that they were fine and that the Lamp had been used the week before. I won the auction and sent off the grand total of £8 plus p&p
I wasn't expecting much so when It arrived a couple of days later (complete with a full tank of paraffin

As you can see it needed a fair bit of TLC. I didn't bother to try and test it as I didn't have any mantles so decided to take it apart and give it a good rub down / clean up. As I'm a typical man I didn't bother with looking for any instructions I just took everything apart that had a nut or screw on it

Nearly all of the rubber washers I came across were totally knackered, It looked like a previous owner had decided that tightening all the nuts and bolts as far as they would go was an easier way of stopping leaks than replacing a washer.
I had a look on Tilleys website and found that they sell a "Washer Set" for £4.50 which also included the Leather Cup that fits in the pump. The Washers arrived a couple of days later along with a Pre-Heater and a few Mantles.

In the meantime S1/gnole had mentioned that the bowl was made from Brass so with a fair amount of elbow grease, wire wool, Wet & Dry, and Brasso, the end result was this

After eventually remembering how to put everything back together
The pump wasn't working. Taking the pump apart I realised that the leather cup inside had disintegrated. Fortunately one was supplied with the washer set I had bought previously so I installed the new one and had another go at lighting it.
Still wouldn't work
By this time I had to accept the inevitable and look online for some instructions, it felt like I was admitting defeat
Anyway, armed with instructions on the correct way of lighting a Tilley (they also pointed out that the control knob is in the "off" position when turned clockwise

All in all it was a good little project. I now have a working and nice looking Tilley Lamp that cost about £12.50 (including the washers) and I have learnt how they work and how they are put together. It doesn't look perfect...but for £12.50, I'm not complaining
A rare success methinks