How steep is the slope?

A sloping fence?

It`s about 10feet in length and goes up about 4feet

Any type of fencing can be adjusted to a slope - depends what sort you want. Difficulty is only that it will probably need to be made to order.
Close-boarded fence panels can be purpose made to quite steep angles. In my current property I had one 4ft high x 6ft wide panel that has about 2ft rise. Best fitted between concrete posts for stability. It lasted 20+ years (until new next door neighbours' children decided to demolish it for fun, aka kicking down something because they were bored)

The usual way of managing a slope with fencing (if you're using panels) is to step the panels down, in other words, the fence posts are set at different levels, but with each panel being level, though lower than the one further up the slope. Means digging out to make level 'steps' wide enough for where the panels will fit, then setting the posts.

many thanks will look into suggestions. Added problem is it`s an old railway bank so all stone, also cost will come in to it, but thanks anyway

Might it be easier to plant a hedge, possibly a dense prickly one?

I saw that you added a photo of the fence area. As the area at the top is flat it should be quite straightforward to replace the fence. If you are getting someone to do it then the fact it is mainly stone is not an major issue as you normally use Postcrete to hold the verticals in place.

Is the fence to go along the top of the bank or down the slope, at right angles to the current fence? I think that down the slope might be better suited to a hedge - it looks very steep! That bank looks like it's crying out for a real rockery.

So where's the picture - I cant see one.

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