I was looking for free GPS satellite navigation system which work on my android phone without data plan and tell me turn by turn navigation. I come across this fantastic free application. I just downloaded this on my mobile from google play store and downloaded free UK map + UK postcodes ( total 450 MB) using my home wifi. When I tested it I found out very useful. I hope this will help people who want free satnav system on mobile.
Note - The road near too my home which was missing in my tomtom map is also correctly showing in this free application.
Update - Link for apple lovers