1. This is not really a slide rule - it is a sliding table. In effect the information of the stock and slide could be put into a table and it would work just as well, though perhaps as conveniently.
2. On the front of the slide, there are columns with the names of towns in the United Kingdom which can be viewed through an opening. By aligning the names of the town you want to travel to with the opening you can read the distance from the town you are leaving from.
3. On the front it also distance to cities in continental Europe from London and table of times when car lights are required.
4. On the back is petrol price calculator which works in similar way to the table of distances. It as starts at 4s 1d (roughly 20.5 p in decimal currency, around 30c at current exchange rates. This would date the rule to around 1960. The current price of petrol in the UK is £3.71/gallon - almost 20 times more expensive.