I wouldn't think a 2005 would have a DPF. Definitely not in UK, but may have been an option in Europe. I had a 2007 freelander with DPF but this was an option. On acceleration could be a sign of turbo boost problem.
Common Causes of Black Smoke:
• Clogged Air Cleaner
• Damaged Injectors
• Bent Injector Nozzles
• Incorrect Injector Timing
• Clogged Air, Fuel or Oil Filters
• Damaged Injection Pump
• Damaged/Clogged EGR Cooler
• Damaged Turbocharger
• Damaged Intercooler
• Over-Fueling the Engine
• Wrong Blend of Diesel Fuel For Temperature
• Cracked or Clogged Valves in Cylinder Head
• Improper Valve Clearance
• Low Compression due to Damaged Piston Rings
• Excessive Engine Sludge Build Up
May be just as simple as it needs a service. Try a diesel system/injector cleaner that you add to the fuel. You can clean EGR and turbo through the air intake pipe with an aerosol.