Therefore, given the accelerated completion of transactions in September and October 2017, and the successful delivery of major development schemes through the second half of the year, we anticipate that the Group's performance for the year ending 31 December 2017 will be materially ahead of the Board's existing expectations.
2017 has proved to be an outstanding year where almost every deal we hoped to complete has done so. Furthermore, we concluded several deals in 2017, earlier than we had originally anticipated, including the sale of the final 30,500 sq ft industrial unit at Thorne, the sale of an 8,150 sq ft retail park in Monmouth and 80 residential units on land in Prestonpans. In addition, the delivery of several industrial units at Markham Vale has, once again, been quicker than forecast.
Within Hallam Land Management, our strategic land division, we have concluded disposals on 14 schemes this year including the final phases of sites at Biddenham for 233 residential units and Marston Moretaine for 183 residential units. In addition, we have already exchanged contracts on four schemes for 2018. Overall, the year to date sales represent 2,048 residential units (2016: 1,609 units).
Within property development, the Aberdeen Exhibition Centre contract is going to plan and delivery of the project remains very much in line with our expectations. We have now concluded all unit sales within the Chocolate Factory at York having originally anticipated that these sales would take place between mid-2016 and mid-2019. Exceeding this target has increased profitability in 2017, by advancing it from 2018/19.
We continue to backfill the opportunity pipeline and work on deals for 2018, thereby replacing the deals that have been executed earlier than expected, and there remains a possibility that some of these may conclude before the current financial year end. With this in mind, together with the wider UK economic backdrop, the Group's expectations for 2018 remain unchanged.