As U.S. gold exports to Hong Kong & China fell 25% in 1st 4 mo's of 2018, London picked up the slack.  According to the USGS, U. S. gold exports to London more than doubled from Jan to Apr compared to the same period last yr.

Interestingly, the amount of gold exported to London during this period nearly equalled the total U.S. domestic gold supply -  64.3 mtons -  up from 25.5mtons.

In the 1st 4 months of 2018:

64.3 m tons to Britain  - 50 mtons to Hong Kong & China  - 40 mtons to Switzerland