Few questions for you - have you pruned it recently? and where is this 'sap' appearing from - the trunk? or a damaged branch?

The sap is bleeding along every branch and it hasn't been pruned. On closer inspection there seems to be a series of old bumps along the branches so maybe it's done this before? It looks sickly and last year only produced 5 pears when other fruit trees in the garden were producing bumper crops

This does not sound good - any chance of a photograph?

I will try but am not good on the computer! Will have to wait for son!

I'm interested in the 'old bumps' - are they orangey coloured?

No they look the same colour and texture as the rest of the branch but are rounded lumps

Then they're probably galls - in association with 'sap' leaking out, I suspect your tree has bacterial canker, particularly if you can find any amber coloured, resin like beads, or if the sap leaking out is that sort of colour.

Bacterial canker usually affects stoned fruits such as cherry, plum, damsom, so very unusual for a pear, though not unheard of. There are different types of canker and the following link may help decide which you have. http://www.which.co.uk/documents/pdf/apple-and-pear-canker-151461.pdf

A tree surgeon could recommend reducing and cutting out the canker to save the tree for the future, but once canker gets in it is a slow decline, so any tree surgeon in the know will also know this.

Thank you so much for your help. I think that is exactly right as there is amber resin on every bump. I think sadly the tree will have to go.