Rolex

Hi, I hope you can help me identify and value this watch. It belonged to my late father, I believe he bought it some time in the 1960's from the Northern Goldsmiths in Newcastle Upon Tyne. I have checked the case and there does appear to be a number under...  

but I could not find reference 6020 in my books. In any case, a classic automatic Oyster from that period. Having it opened could help determine if it is 14 or 18k gold, but that would not affect much its value. Cheers Jeff

Is it easy to remove the back or do I need to take it to a pro?

so take it to a pro. Cheers Jeff