Strong performances across its businesses in December saw real estate advisor Savills revise its full year estimates upward.The group said that it now anticipated its underlying results for the calendar year to be "well ahead of our previous expectations", after revenue and profits for December significantly exceeded expectations.The firm, which on 18 November announced it expected its underlying results for the year to "at least" meet its expectations, cited the completion of a number of sizeable transactions in the UK and in Europe among the driving factors behind a strong finish to the year.The rise in stamp duty on high value UK residential transactions which caused a short term increase in trading volumes and the successful close of a new Nordic Logistics Fund earlier than anticipated also contributed to a stronger-than-expected performance in December, Savills said."For 2015, we retain our cautious stance particularly on the performance of the UK Residential market in the first half of the year, as a result of continued uncertainty around the UK general election, and the timing of a sustainable recovery in Hong Kong," the group added.Savills shares were up 7.44% to 700.50p at 08:25 on Thursday.