Pollarding 

Pollarding is a practice that I would discourage as it stresses the tree due to the severity of the pruning which results in a sprouted epicormic growth. It is traditionally done to certain trees to prolong their life and so graze cattle below with the new shoots out of the way of grazing animals. There are certain trees like London plane, poplar and lime which are hardy enough to be pollarded.

When a tree has been pollarded previously it is often best to keep doing it but sometimes through careful and successive prunings a natural crown can be reestablished  over many years. Many front gardens in London have trees which are pollarded and under a TPO, Tree Preservation Order which means that there is a limit to what you can get done with a simple re-pollard being the most common option.