Accepted the job offer -- just wanted to thank everyone for the positive support!
FWIW, I was naughty and actually left the piercing in when I went for the first interview with this company, because I was ill and couldn't be arsed and didn't think I was going to want the job anyhow. It's a history best told over pints, but I obviously have some lingering PTSD from the last company I worked for in the same sector (albeit in the States), so I was prepared to hate this one. (Am well aware how irrational that is.)
But I didn't! I love them! And they love me! And there's delight all round with my hiring!
Thanks again, everyone.