Summary of the English Law of Liens from Halsbury's Laws of England:

Key Points:

1. Types and Basic Definition:
- A lien is fundamentally a legal right to keep possession of property until a claim has been met
- Types include: legal, non-possessory, equitable, general, particular, statutory, contractual, judicial and subrogatory liens
- Multiple types can exist concurrently

2. Main Categories:

Legal Liens:
- Arise at common law
- Require rightful and continuous possession
- Don't typically require a written agreement
- Act as a defense rather than a right of action

Equitable Liens:
- Arise by operation of law independent of possession
- Similar to equitable charges
- Don't necessarily require a contract
- Subject to equitable principles and conditions

Statutory Liens:
- Created by statute
- Interpretation depends primarily on statutory meaning
- Can override or nullify other types of liens
- May be general or particular

Contractual Liens:
- Arise from contract terms
- Primary interpretation based on contract language
- May supersede other types of liens
- Strictly construed, especially for general liens

3. Important Distinctions:
- Liens differ from mortgages, pledges, bills of sale, and equitable charges
- General liens allow retention of property until all claims are satisfied
- Particular liens only allow retention until specific charges are paid
- Legal liens typically require possession while equitable liens don't

4. Key Characteristics:
- Most liens require possession to be maintained
- Cannot typically be assigned without owner's authority
- Holder has duty of care for the property
- No inherent power of sale (unlike mortgages or pledges)
- Registration may be required depending on type

This is a complex area of law where multiple types of liens can coexist and interact, with different rules governing their creation, maintenance, and enforcement.​​​​​​​​​​​​​​​​