IIRC
Have seen it in the UK, and the stuff is a pre-wash or pre-soak product. Contains enzymes and such for removal of stains.
One assumes such products were found in the UK, due to so many detergents being "non-bio", thus not containing enzymes which are required to shift goo, poo, and other stains.
Enzyme prewash and presoak products were common in the United States, but again that was before most TOL and MOL detergents such as Tide began adding enzymes to all their formulas. Now only products such as All, Purex and a few other brands do not contain enzymes.
L.