The phrase "allegedly based" is correct and usable in written English.
It can be used when discussing claims or assertions that are reported to be true but have not been definitively proven.
Example: "The documentary is allegedly based on true events, although some details have been disputed."
Alternatives: "reportedly based" or "supposedly based".
The pivotal, though hazily defined, figure is Guy Littleton, a philanderer allegedly based on Ian Fleming.
It is allegedly based in New York, taking payments in pounds and forints.
He was allegedly based in a secret command centre in the Kuwait hotel on the city's eastern outskirts.
A society was defined by its mode of production, on which its political, juridical, and ideological superstructures were allegedly based.
The jury was told of the stories which subsequently appeared in the NOTW, allegedly based on the hacked voicemails.
Belgian investigators were alarmed to learn that the French driver, allegedly based in Molenbeek, had a brother fighting with Islamic State in Syria, according to local media reports.
Talk story about writer Barbara Chase-Riboud's lawsuit against filmmaker Steven Spielberg's studio, DreamWorks SKG, for allegedly basing parts of their new film "Amistad," about a slave mutiny in 1839, on her novel "Echo of Lions".
Both allegedly used computers based in the UK to run illegal networks.
Allegedly, Driveshaft are based on Oasis because Charlie and singer Liam are northern brothers, but in the performance footage they look more like confused male models playing a rock band in a Gillette advert.
The organised crime group allegedly used hackers based in Belgium to infiltrate computer networks in at least two companies operating in the port of Antwerp.
The EU has "rubber stamped the widespread removal of allegedly illegal content, based only on flagging by third parties," O'Brien said.
