Where is the second longest river in England?

The river Trent at 185 miles long, flowing through Stoke-on-Trent, Lichfield, Derby, Nottingham and Newark-on-Trent.

Its source is Knypersley near Biddulph, Staffordshire and its mouth is the Humber Estuary.

This is a very detailed and succinct answer. However, the Trent is the third longest river after the Severn and the Thames.