we have just moved into a new house and we have a victoria plum tree that as been neglected it is far too big for the garden it stands about 12' high and about 12'wide will it stand severe pruning in height and width thank you
What I would do is wait until june /july next year. Don't prune before that or there is a risk introducing disease.
In June / July prune about a third of the length of the branches. Aim for a goblet shape with the central part of the tree being relatively free of growth. That will allow air circulation and help protect from disease.