How to name alkenes?

I’m looking at this structure and I think it would be 3-bromo-4-fluorohex-1-ene

But I have seen places on the internet calling similar compounds something like 3-bromo-4-fluoro-1-hexene. 

My question is would it be -1-hexene or hex-1-ene? And does this apply to all alkenes/when would you use each one? 

I am in England if that changes the naming system.