With the Whittaker, you wait until you’ve had two losses in a row and then you add those two losses together to give yourself the next betting amount. So you would start out by betting £1 and you would keep betting this amount over and over until you get two losses in a row. Assuming you start with 1$, your progression would look like this as the losses add up.
1 – 1 – 2 – 3 – 5 – 8 – 13 – 21 – 34 – 55 – 89
The Pluscoup Progression is a modification of the Oscar's Grind and has many similar variations. It is too a positive progression or "up as you win" progression initially invented for the even chances like Red/Black, Odd/Even and High/Low. The Pluscoup Progression is a very shallow progression, raising the bet size very slowly. It is a slow-earning betting strategy and in theory you can make a lot of money using this strategy, a large bankroll, and an enormous amount of patience.
A fairly conservative roulette player once compared the probability of the outside, even-money bets hitting as being similar to a pendulum. He theorized that the odd/even, red/black/, and high/low bets would hit with some regularity on either side, but rarely did one side hit 10 times more than the other in any session of play.