9:00 isn't that slow. Wejo was running 7:30 to 8:00 pace when he ran 28:06.
When I was in shape to do 6 miles tempos in under 30 minutes in training, my average pace was around 7:45.
I just looked up my first marathon (I've only run two) in 2012 when I was 43. I ran 2:54 after starting to cramp 20 miles in. Sure, my training was not at all optimal for a marathon, but I run mainly because I enjoy being out on the trails and in the mountains. I was just running, and not doing specific training for a marathon. My average running pace according to my training log for the 13 preceding weeks, along with the fastest run(s) of the week:
82 mile, 10:48 pace, the marathon @6:37 pace, 9 miles @7:20 pace
97 miles, 13:36 pace, 12.1 miles @6:47 pace
81 miles, 11:16 pace, 13.4 miles 2,076 ft climb @8:27 pace
98 miles, 10:41 pace, 27.9 miles @7:36 pace, 12K race @5:48 pace
106 miles, 9:58 pace, 5.55 mile 2,000+ ft climb @8:53 pace, 5.3 miles @7:33 pace (warm up for orienteering race)
120 miles 11:12 pace, 13 miles @7:28 pace
104 miles, 10:51 pace, 7.4 miles @7:34 pace
98 miles, 10:34 pace, 14.5 miles (hilly) @7:48 pace
115 miles, 12:06 pace, 9 miles (hilly) @7:43 pace
89 miles, 11:27 pace, 9.4 miles (hilly) @7:40 pace, 15 miles (rolling) @7:56 pace, 1 mile on kind of snowy track 5:30
42 miles, 11:32 pace, 12.65 miles (very hilly) @9:15 pace
130 miles, 10:09 pace, fastest run 20 miles, 4,300 ft climb @8:51 pace
38 miles, 12:33 pace, fastest run 9.1 miles @9:01 pace
A lot of those miles were slow, walking pace jogs with my old dog. I had maybe less than 10 miles (non-downhill) total in the 13 weeks preceding the marathon that were as fast as the marathon pace.
I haven't been good at long races like the marathon or long trail runs probably because I don't do marathon specific training (and the resulting slow average pace). My shorter distance speed is decent. Up until I was about 40, I could pop a sub-5:00 mile at the end of long runs whenever I felt like it. When I in my late 20s, I could knock out sub-4:40 miles at the end of long runs even though I wasn't training and hadn't raced in a couple years.