I've always struggled with stamps like this, and then I remembered my craft stash had moved on, and tried it with Black Archival. Bingo
It's a Michael Powell stamp from Docrafts, painted with Distress Inks. It's the first time I've stamped it successfully, and would have been my first time at Sunday Stamper.
I was going to enter it into Hels Sheridan's Something New challenge, but didn't get it uploaded in time. So I think I'll allow myself a double link and submit it to Simon's Says Stamp's Monday Challenge as well, which is also 'Anything Goes'.