Inventory

12 Months Ended

Dec. 31, 2018

Inventory [Abstract]

Inventory

15.  Inventory

At each period end, inventory is reviewed to ensure that it is recorded at the lower of cost and net realizable value. During the year ended December 31, 2018, the Company recorded an inventory write-down of $1,011,000  (2017:$834,000; 2016: $3,084,000).