Hi Neil,
Being new to this forum, and new to my 230SL, I don't have an answer to your two questions. However, I would ponder to guess that your problem might be either the coil springs, or more likely a shock that has given up.
I know when I first picked up my 66 230sl, it was leaning to the right in the right front corner of the car. After asking some questions on this forum, and taking a closer look, I found that the right front shock had collapsed. The rest of the shocks, are just about as bad, however, they are still good enough to keep the car at it's proper level.
In any case, if you are taking the car to someone to do the work other than doing it yourself, it might be wise to come back on the forum and let everyone know what your mechanic came up with.
Take care,
Tom