I don't think this price rise is the most sensible option for Tesla.
The Model S is already at a super-premium price point, interest rates are low and commodity / raw materials prices are falling. Couple this will falling fuel costs, means that overall the Model S package is increasing less attractive as a purchase option compare to 12 months ago. While the MS is relatively new to the UK, it is now in its fourth year of production, usually this would be a downward inflection point on price.
Maybe this is more a result of the stronger dollar. However if the dollar weakens I doubt we will see prices fall.
A lot of the press / analyst reviews (aka beatings) have come at missed sales targets, not poor margins; these increased prices will not help their cause.