Also the 10km pace won't be her marathon pace. Marathon and 10km races are extremely different. Even a half-marathon pace doesn't translate into a marathon pace. Especially at London where the course has some hills. But a 40 min 10km pace is still extremely impressive even on a treadmill. I'd wager if she's running 40-50 minute 10km pace outside she'd be looking at a <3:30 marathon, which is great. It depends what her current highest-threshold run is right now, but if it's anything over 20km then at this point she's very prepared, and she might even be able to improve her pace between now and London. But, her goal might just be to finish! I care about my running times a lot but in my first marathon, my goal was just to finish haha!