That link is for A class tanks, but the B class tank page also has plenty of colour shots... with yellow axle boxes!
Don't know how I've missed those previously... very poor!
https://paulbartlett.zenfolio.com/essobtankwagonvb
Pretty conclusive I think...
p.s. time to get the yellow paint out...
Having checked in my copy of Geoff Kent's book, it seems likely that the axle box covers on class A tanks might be yellow, especially when new; however, he sadly fails to mention any colour for the class B...
My choice would be this...
Positionable photo mount adhesive sheets
Also available in rolls, I think about £85 for a 0.4 x 30 meter roll! Would last for ages...
Alternatively, a similar product...
https://www.selfadhesive.co.uk/tapes/double-sided-tapes/adhesive-sheets.html
When I had a similar issue, it was suggested (by John Isherwood himself I think!) that I buy the necessary sheet, use the required item and then sell the remainder...
The last time I bought some it was no longer blue...
...I hope it's the same as I have two bottles!
I haven't used it yet as I still have a little of the original blue stuff left.
p.s. Thought I'd better check that I hadn't been sold two bottles of water! All seems okay, it works.
There's no info on the website to suggest there's been any sort of problem, or indeed any updates at all.
It's a good start, but I think I'd be inclined to email first to see if you get some sort of response...
Thinking about it I'd be surprised if there isn't someone on this forum who knows more?