tick over 2000 rpm

Hi all Ive just bought a 53 plate td4 from ebay . Ive never drove a diesel before let alone a land rover so please excuse my ignorance.I thought everything was fine drives great ,nice and smooth and better on diesel than I thought it would be BUT I was sat at the drive through this morning and noticed that the tickover is at nearly 2000 rpm and after reading on here that it should be around 780 rpm I'm a bit worried that my bargain is gonna cost me £££s.Could the person ive bought it of raised the rpm to hide any problems and what would be the cause of such a high tick over (when I got to work I turned all lights fans and heater of and it made no difference)Thanks in advance for any help