I've just downloaded this onto my phone and I see - with horror - that next to the barcode it says that the pass expires after a few weeks 
Does this mean that on a regular basis we all need to download a new NHS Covid pass?? I found it a complete pain to get - taking a video of myself reading out four numbers, wtaf?? - so don't relish having to do it again or, even worse, being en route somewhere and realising that it's out of date...I mean, why does it expire??