The Non-Road Mobile Machinery (NRMM) Stage 1 regulations start September 2015.
The NRMM Stage 2 regulations start September 2020.

Stage 1 NRMM regulations from September 2015 means any NRMM operating in Outer London (also known as Greater London) must meet as a minimum Interim Tier IV or Euro Regulations IIIA.

Stage 1 NRMM regulations from September 2015 means any NRMM operating in Inner London (also known as Central Activity Zone and Canary Wharf) must meet as a minimum Full Tier IV or Euro Regulations IIIB.

Stage 2 NRMM regulations from September 2020 means any NRMM operating Anywhere in London must meet as a minimum Full Tier IV or Euro Regulations IIIB.

Link to full article