12 Investments

Group£m
At 1 April 20146.9
Additions0.8
Currency translation differences0.9
At 31 March 20158.6
Disposals(0.2)
Currency translation differences0.3
At 31 March 20168.7

During the year, the group reduced its investment in Muharraq Holding Company 1 Limited through a £0.2 million repayment of a shareholder loan.

During the year ended 31 March 2015, the group increased its investment in Muharraq Holding Company 1 Limited by £0.8 million.

At 31 March 2016, the group's investments mainly comprised its investment in Muharraq Holding Company 1 Limited. These investments are held at fair value.

CompanyShares in
subsidiary
undertakings
£m
Cost
At 31 March 2016, 31 March 2015 and 1 April 20146,326.8
Impairment
At 1 April 2014726.8
Reversal(726.8)
At 31 March 2016 and 31 March 2015
Net book value at 31 March 2016 and 31 March 20156,326.8

In the year ended 31 March 2016, a review has been performed supporting the carrying value of the £6,326.8 million investment in United Utilities PLC.

During the year ended 31 March 2015, the review resulted in the reversal of an impairment made during the year ended 31 March 2010. The reviews are based on a 'fair value less costs of disposal' valuation.