To be honest Op, there are usually a large gap between the lower attainers in early years and y1, and the top attainers. Teachers are used to this, in happens in most classes. At our school, teachers have been ok at supporting the more able children but not by giving them an early label of Gifted.
Our schools doesn't not nave a policy specific to G&T children but they generally support them through more advanced reading schemes, small group work, extension work especially in maths, but in my experience (I have children in y5 and 6) G&T is more obvious when they reach year 3 and 4. In the infants years, many will catch up, and attainment is fluid so children that were middle attainers in infants may suddenly 'bloom' into more able children.
At the moment many schools are taking the approach of 'mastery' for more able children, as opposed to just going through the curriculum as fast as possible. So more able children are encouraged to apply their knowledge on complex problems and are encouraged to be able to demonstrate a deeper understanding of the item (as opposed to ticking boxes and moving on to the next topic).
My youngest DS is very advanced in maths, and ahead in all subjects. We have found that some teachers are better at understanding how he works and what makes him tick, whereas other teachers have just been able to support him as opposed to challenge him. But this is the same for all children - the style of teaching will be a fit for some children and not others. We have never, however, walked up to a teacher and says 'my ds is very advanced what are you doing about it'. It was more a question of discussing how he can be supported in the classroom alongside his friends.
Just to say, also, that a vaste majority of children, whatever their attainment, do get bored at one point or another in their learning days... I was pretty average at school and bored most of the time...