IIRC estate rear camber is less than saloon (slightly more upright). I believe the only difference is spring length with all other parts the same. The difference in camber is caused only by the estate's suspension sitting higher.
If you appear to have excessive negative camber, check the inner edges of the rear tyres for excessive wear (providing they haven't previously been on the front!). If there is too much toe out, this can cause the camber to appear incorrect as the trailing arms' bushes will be strained out of their normal position.
There is an adjustable link rod which can wear at the ball joint or the inner bush (usually soaked in diff oil) can become soft with age allowing wheel alignment to drift out of tolerance.
First thing to check is rear toe out before proceeding further...