If its a broadleaved tree, then probably not, but it would be nice to know what the tree is to give an accurate answer.

Bamboo is right, the only way to give a good answer is to know what kind of tree it is. That said, plain, brutal topping is rarely good for any kind of tree. I would use a combination of thinning out weak branches, and cutting some of the longest ones back to vigorous side branches. I would probably also raise the canopy to let more light in from the edges. Let your inner bonsai artist free!

Have you applied for a tree work application from your local council? Even if the tree is yours, you must apply before starting work. The council tree officer will tell you what pruning you can carry out.
If you don't, you could end up with a hefty fine and a criminal record!
I don't know if this is so in Ireland but it is in England.