Thank you for the comments. I try to make the blood look "Old" and don't actually use red, tending to go for GW Dark Flesh which is a nice red/brown colour.
I make my zombie blood similarly, thoughI use watered brown ink (with an extremely small amount of black) and mix in a little of what is called 'Watermelon Red' from a cheap acrylic paint line (Crafter's Acrylic) I use for terrain painting. It has a different consistency to GW's stuff that gives the mix a 'redish' feel but also gives it that dry blood texture because the paint drys a little chalky regardless of how thin or thick the paint is. That gives it the coagulated texture for the dark brownish/redish dry blood on my zombies.
One time when I had a bit of excess of this mix, because I had to stop painting, I tipped the mixing pot right over my painting setup (without forethought I hasten to add) and it actually looked like a bad accident had occurred on my workbench. Should have seen how my mum reacted upon seeing that ghastly mess the next day when I was otherwise alluding her sight in the attempt to scare her (which is too easy as it is). And she's well aware of my frequency for hacking up my index finger while reshaping bits of plastic. I know, I'm terrible.
Can't wait for that chimney-sweep! There should be a Mary Poppins sized collection of those fellows.