How come there were 2 series shown in 2004 and what was the reason or reasons behind it?

After series 4, the interval between each series has been 12 months, but this was not the case for the first 4 series.

There was:
8 months between series 1 and series 2.
9 months between series 2 and series 3.
10 months between series 3 and series 4.

Don't know why, but it seems that they could not settle on the regularity of the show for the first few series and it just happened to be that series 3 and series 4 were on in 2004.

Link

Thank you, that has put my confused mind at rest.

We should have two series a year again

They can hardly scrape together 10 celebs to one a year, unless we want wall to wall reality 'stars' gracing our tellyboxes.