From the article...
The warehouse had to be closed for six hours on Tuesday amid fears it could be poisonous.
Made me laugh 
I know,that is what we found funny but watching 'Wildlife SOS' the other night was a woman & what I presume to be her son & they didn't recognise one either. So I conclude from that that the majority of the population does not know how to recognise a grass snake from an exotic or adder. I have never seen one in the scale as you might say but I known they are greenish brown & have a yellow collar. Xeracts decapitated snake was a bit between for me, so hard to tell. But to think that amongst a load of grown men there was not one who could recognise it as a grass snake is funny , at least they didn't kill it ...Nice story though & hopefully he will be let loose in a habitat that is suitable for him.
Yes the main thing is that he was rescued and taken some where safe. You have to give the men credit for not trying to hurt it, they did think it was a killer after all!
Even if they didn't know what it looked like for sure, a quick google search for snakes in the UK would have revealed pictures of all the native types and they would have realised it was harmless.
Just what I needed to confirm it was a grass snake I saw the other day. I was out walking through woods and it went across in front of me and I just caught a quick glimpse.
I haven't seen a grass snake for a while that I can remember. Quite often it's difficult to tell between them and adders when you just get a glimpse.