Originally Posted by
Globaliser
It may just be telling you that having earned 600 TPs in the current membership year, that has been enough to maintain Silver in the next (2017-2018) membership year - which is true.
To maintain Silver beyond that and into 2018-2019, you must earn at least 600 TPs and have taken 4 qualifying flights between 9 November 2017 and 8 November 2018.
Thanks! Guess I won't be keeping silver in 2019 then.