Garages and testing stations will be required check for a diesel particulate filter (DPF) in the inspection of the exhaust system as part of the MOT test (or annual test for heavy vehicles) from February 2014.
The vehicle will automatically fail the MOT test if the filter had been fitted as standard but is found to be no longer present.

https://www.gov.uk/government/news/new-rules-for-mot-to-test-for-diesel-particulate-filter

Stuart