One way of looking at the surge in price is...
BDR suiter GPL shares went up another 6% to 71 US cents on the 31st Dec.
Thisvalues BDR shares per the scheme at 6.3 cents.
A technicaltrend up is in place for silver. Likely to test $16 in near term, which is goodnews for GPL and therefore BDR shareholders.
GPL has 3 brokers in America with strong buy recommendations. Not surprising as they get BDR for bugger all.
This article explains the silver movement very nicely and prospects for 2019.
https://www.kitco.com/commentaries/2018-12-31/Silver-Starts-A-Breakout-Move-Higher.html