" It seems a bit odd to have plug leads jammed up against one another like this"
Not at all. If there is a danger that the 40,000 volts (30,000 for a standard coil) is likely to earth through the insulation, that indicates poor insulation and a sub standard product.
My car doesn't have the original HT lead tube, but all the leads are zip-tied together. They have been this way for 60,000 miles. The only ignition failure was the coil in this photo, which failed after about 20,000 miles. The car now wears a genuine Lucas sports coil.
