2003 Rover 75 White smoke

Hi,

I have a Rover 75 1.8t. I have had a few months worth of problems (HGF!!) that resulted in having a new engine fitted by the garage I purchased the car from. (Engine was from Ivor Searle)
By my own admission I slightly overfilled the engine with oil, that was soon drained (within several hundred miles, as it was smoking a little)
The problem I have now is that there is a great billowing of whitish/grey smoke from the exhaust upon start up. I cannot leave the car to idle now to see if it will go away as there is just too much smoke.
Can anyone advise as to the cause? I have changed the oil and filter, to no avail.
I have read up much on what the possible causes could be..
HGF - New engine only on 1.5k with no tell tale signs.
Turbo seal - Seams clean and oil free (what I could see)
Emissions sensors - No clue I'm afraid
Coolant getting into engine - No clue
Cat Converter - No clue
I have included a photo (on start up - before the real fun starts)
Please help - I have had my car for 8 months and hardly driven it.

In Anticipation - Many Thanks

Steve