Bummer, Simpson is not entered in the Women 1500m, but Hasay, Rowbury, Martinez and Uceny are:
http://www.diamondleague-london.com/Live-StartlistsResults/Overview/1500m/
Manzano is entered in the Men 1500m:
http://www.diamondleague-london.com/Live-StartlistsResults/Overview/1500m1/