In a nutshell, huge list of checks!
Here is the complete list:
Convictions and Sentences Imposed Outside of the UK
Convictions and Sentences Varied on Appeal
Persistent Offenders
Offences Which Cause Serious Harm
Sexual Offences and the Sex Offenders Register
Fines
Fixed Penalty Notices, Penalty Charge Notices & Penalty Notices
Cautions, Warnings and Reprimands
Community Sentences
Confiscation and Forfeiture Orders
Civil Orders
Hospital Orders & Restriction Orders
Considering Cumulative, Non-Custodial Sentences
Pending Prosecutions
Failure to Disclose Convictions or Criminal Proceedings
Extradition Requests and the European Arrest Warrant (EAW)
Suspected Criminal Activity
Involvement with Gangs
Association with Known Criminals
Proceeds of Crime and Finances of Questionable Origins
War Crimes, Crimes against Humanity and Genocide
Terrorism
Corruption
Public Order
Exclusion from the Refugee Convention
Bankruptcy and Liquidation
Debt
Dishonesty in Relation to Public Funds
Non-Payment of Council Tax
Parenting
Deceitful or Dishonest Dealings with Her Majesty’s Government
Failure to Disclose Convictions
Deception in previous applications
Bogus Marriages/Civil Partnerships and Marriages/Civil Partnerships
Abuse of the English Language and/or Knowledge of Life Test
Prosecution for False Statements
False Statement by Referees
Illegal Entry
Assisting Illegal Migration
Evasion of Immigration Control
Hiring Illegal Workers