You best bet is to get advice from a tree surgeon in your local area. Make sure that whoever you contact is an actual tree surgeon, though, and not just a man with chainsaw who knows nothing whatsoever about plants / gardening, and will happily hack down anything for a fast buck!

Hi

Most start looking old when hitting 50 and the problem is the roots lose the strength as you have found with the tree leaning over

best to take out and replace

Rosemary Verey’s famous laburnum walk at Barnsley House had the chop last year as well.

Gg