That's right. There was an early series where the votes produced a Children in Need donation. Every week they announced how much was raised in total, so it was easy to work out how many votes were made. Voting was a little different then, the votes were phone only and were open all week. That is, you could vote before anybody danced, so it really was a popularity contest.

What was noticeable was early weeks attracted few votes. The numbers grew week by week and semi finals and then finals brought out far more voters. Given the relatively small numbers of votes, and split between a greater number, the voting patterns in the early weeks can be quite variable.

What has been worked out from what can be calculated, and a few partial leaks - probably from mobile companies, is that there are those voting out of sympathy for finishing low, or judges remarks they consider unfair, or last week's "saved" dancer. It's obvious from the later stages that many vote largely with the judges, on dance criteria. Combine those influences with the show encouragement to "vote to keep your favourite in" and you get the "dangerous" middle.

From the judges board, the top places get public votes, the bottom get public votes. The middle places are forgotten or assumed to be safe and get few public votes. Some claim to be surprised, but every year, often when there are more than ten left, the dance off will have one or both from the middle of the judges board. The effect is more likely if several dancers are tied and many dancers are separated by few judges points. Hence Laura and Tameka. The judges always choose to save the more conventionally competant dancer, the "character" dancer will be out. Unfortunate for Tameka, but just the way it works.