are the thick, fleshy, thorny, red, vigorous shoots that have appeared on a rambling rose near the top branches. Can you tell me if this is a type of sucker?

If they're suckers, there'll be a different number of leaflets in each leaf stem and they're usually a lighter colour than the rest of the rose. So if your rose has, say, 5 leaflets in each stem, and the new growth has 7 and is pale coloured, then it's a sucker. It is unusual, though, to get suckers from higher up the plant, unless the graft is high up, which you'd normally only find on a standard. A photo would be good, or the name of the rose.

Sounds like vigorous new growth to me - quite normal for ramblers.

I think you are looking at a very happy rambler getting ready to take off! The leaflets below a bud are usually only three...then a bud...that's why when you deadhead you must prune back to a viable bud (usually outward facing) just above a five leaflet... Agree with Wagger.