Wear on inside of front tyre??????

[LordBretSinclair]

Hi all, I would appreciate your help with the following. The inner edge of the front offside tyre on my DB7 Vantage is wearing really bady. Tracking I thought. Just had it checked at my local garage (I know the guy well and he really took his time and did it really accurately). The reading was half a degree toe in.
We couldn't find the correct reading on his computer - it didn't list any AMs, so first question -is this reading about right, what should the toe in be? Secondly if the tracking is OK any ideas on why the offside tyre is wearing on the inside when the nearside tyre is perfect?

many thanks, regards all, Lord Brett