Harriet Harman escapes driving ban

The Labour deputy leader Harriet Harman has been fined £350 (as well as ordered to pay £75 costs and the new victim surcharge of £15) and given three points on her driving licence after pleading guilty to driving without due care and attention. Oddly the second charge of driving while using a mobile phone was withdrawn. Why was the charge dropped? Was it because drivers convicted of using a mobile phone whilst driving receive an automatic three-points penalty and a maximum fine of £1,000? With the six points previously on her licence Harriet Harman, plus the three for driving without due care and atention, she would have been disqualified from driving. I note that witnesses at the scene of the incident claimed that Harriet Harman was using her mobile telephone. I am of course sure there is a perfectly innocent explanation for what happened in court today.