Thankyou all, some fantastic ideas, ordering the parts as we speak! A brilliant start to my time on this forum!

Hi All, Im new here and drive a 1998 300 TDi Defender 90, have seen a lot in the news, social media act about Defender thefts and was looking for some of the best, cost-effective theft deterrents I can fit to my Defender, (Wheel locks, immobilisers etc?) What would you recommend? Cheers,