Sub-Mariner (1968 1st Series) UK Edition comic books 1974

UK edition. Identical to US edition, but has 6p cover price. Cover by John Romita. "On the Brink of Madness!", script by Steve Gerber, pencils by Don Heck, inks by Jim Mooney; Namor returns to his underworld realm to find it devastated in the wake of the nerve gas contamination; Fortunately, his subjects are just in a comatose state and amphibian scientists are eager to help them; Namor takes the scientists to Dr. Hydro's island base and then seeks out Dr. Walthers who has been working on a force field device that can protect Atlantis from any other nerve gas contamination; However, the costumed villain Force stands in his way. Namor drives him off and continues his search for Dr. Walthers; Cameos by the Inhumans, the Fantastic Four, and Spider-Man. A note from Roy Thomas and Steve Gerber explaining a printing error on 50,000 copies of Sub-Mariner #68. Ad for Man-Thing and Ka-Zar. 36 pgs., full color.

UK edition. Identical to US edition, but has 6p cover price. Spider-Man guest-stars in "Two Worlds and Dark Destiny." Script by Steve Gerber, pencils by George Tuska, inks by Vince Colletta. The letters page includes a Marvel Value Stamp. John Romita Sr. cover?