Spoilers for Attack the Block
Why were the male gorilla/wolf aliens coming after Moses and his friends rather than the carcass of the female alien, which was presumably Pheromone Central and must have had a much stronger scent than the traces left on Moses and the others’ clothes? (This must be, of course, why the carcass was part of the final bait along with Moses–also it had to be burned anyway to keep away the other aliens.) Is it because the weed room where the carcass was kept was insulated from smells to avoid detection? This seems the likeliest explanation, since the male aliens weren’t coming for the weed room once Moses and the others got behind the door but rather crowded outside. This is consistent with them losing the trail and hovering at the last place where they had the scent.
Which is kind of mind-boggling in its own way. These pheromones can cross outer space but they can’t get past a weed room’s scent insulation, evidently. Who knew weed dealers were our line of defense against alien invasions? Respect.
Also, is there a chance another female alien could land on Earth, drawing males after her? If so, Earth is fucked unless the authorities–or an audience of violent tin hatters, which seems likelier–listen to Moses and the others’ story. Unless they know to shoot any further female alien from a distance and then napalm the carcass, then thoroughly cleanse any trace of the pheromones on people and the surroundings under UV light, there are going to be repeat landings of male aliens and more deaths.
I’m also trying to figure out how reproduction works for this alien species. If the male:female ratio in the movie is representative for the species as a whole, and assuming male and female are even vaguely analogous terms for this species, maybe it works like a queen ant mating with multiple males and storing their semen for years to fertilize and lay eggs at her leisure. We may have been watching something like an ant mating flight in progress, only to be violently interrupted by Moses.
I mean Moses regretted what he did, but would things really have been better if he didn’t kill the female alien? He himself was already marked by the pheromones just by their initial contact (First Contact, if you will) when she pounced on him, and probably the same people who had been marked by touching him in the original timeline would have been marked even if he had let the alien go. Maybe there would have been a smaller pheromone footprint on him, since he would not have had the queen’s pheromones all over him from killeng her, and so fewer people might have been marked, but that’s about it.
But really, best case scenario, even if Moses hadn’t even reached into the car and never come into contact with the queen, she would have touched and marked someone eventually in a city as crowded as London. The males would have arrived and killed the people who were marked. They could have arrived in even greater numbers without her scent being shielded by the weed room (remember, our planetary line of defense). And if the queen had lived and successfully mated, there would have been aliens born on Earth to wreak havoc unless she moved on elsewhere to give birth/lay eggs. All in all I can’t think of Moses killing the alien as a bad thing, though his intentions at the time were not noble.
Tl; dr AtB is a movie about how weed dealers and disaffected teenaged boys are our best defenses against an alien invasion, God help us all.

@jewishcomeradebot True, I don’t think the army and police, as opposed to inidividual and generally rogue soldiers and policemen, have ever been an effective force against an alien invasion in the history of cinema. The PacRim series are the closest I can think of where an official, sanctioned military group held their own against aliens, and even the Jaeger program was the result of the conventional military’s utter failure against the kaiju.