out of hours implied contract

[hullboy]

I have worked an out of hours scheme for my company for 4 years but isn't in my contract. I have now been told that I will not be on the scheme anymore and will get some notice and 1 year pay protection. My question is does that period of doing the role, even if it is an add on in effect, entitle me to implied terms? Also our policy is 2 years pay protection when moved from job etc , would this also apply to an out of hours scheme too? Don't just want to roll over and give up on this if I don't have to. Any advice appreciated. Thanks.