Route 521
Route: Little Lever - Farnworth - RBH
Operators
| Operator | Start date | End date | Notes |
|---|---|---|---|
| Blue Bus | 29/07/2005 | 1550 St Joseph's RC High School to Royal Bolton Hospital (Schooldays only). Start date to be confirmed. | |
| South Lancs Travel | 27/01/2007 | Start date to be confirmed | |
| First Manchester | 23/02/2004 | 30/08/2005 | 0745 Four Gates, Blue Bell Farm to St James CE High School (Schooldays only). Renumbered to 990 |
| Arriva Liverpool | 01/08/2005 | 05/09/2005 | 1550 St Joseph's RC High School to Royal Bolton Hospital (Schooldays only). Transferred to Arriva North West licence. |
| First Manchester | 04/09/2006 | 27/08/2010 | 1550 St Joseph's RC High School to Royal Bolton Hospital (Schooldays only) |
| Lancashire County Transport | 29/01/2007 | 26/01/2008 | |
| Vales of Manchester | 28/01/2008 | 17/05/2008 | |
| Wigan Coachways | 20/05/2008 | 16/08/2008 | Emergency contract in place of Vales |
| South Lancs Travel | 18/08/2008 | 14/01/2017 | Continues as Diamond Bus North West |
| Arriva Liverpool | 31/08/2010 | 23/07/2011 | St Joseph's High School - Westhoughton Church - Bolton Hospital |
| Arriva North West | 25/07/2011 | 30/08/2015 | 1550 St Joseph's RC High School to Royal Bolton Hospital (Schooldays only). Transferred from Arriva Liverpool licence. |
| Diamond Bus NW | 16/01/2017 | 22/04/2017 | Continuation from Green Triangle Buses (formerly trading as South Lancs Travel) |
| Cumfybus | 24/04/2017 | 30/03/2019 | |
| Tyrers | 01/04/2019 | 27/04/2019 | |
| Go Goodwins Coaches | 29/04/2019 | 10/04/2021 | |
| Vision Bus | 11/04/2021 | 23/09/2023 | |
| Diamond Bus NW | 24/09/2023 | Farnworth-Blackrod Small franchise (Bolton Depot) |