The thing with that sort of promotion is that it doesn’t sustain in the same way that word of mouth does.
It’s not a continual thing that you can rely on. It is great to have, and I’m sure Starling are very proud of it though! So congratulations to them! 
We believe in making our app so helpful and delightful that people are bursting to tell their friends about it because it’s been such a positive influence in helping them control their finances. That kind of growth really is something you can’t buy.