I don't have much faith in the No 10 Petition facility, but really this was a very poorly worded petition.
"ALLOTMENTS are conspicuously few in the UK today and according to my research the government is breaking the law by not providing enough"
They're clearly not "conspicuously few". Like Taurus in Swindon, we in Harrow have literally dozens of plots, including two whole sites, going begging. If the petitioner is criticising some councils, and asking for Prime Ministerial pressure to be brought to bear, they should have said so.
If the petitioner had actually done his or her "research", they would have known that the government wasn't breaking the law. That's why the response pointed out what the law actually is.