squatters rights

a farmer has been farming a farm for 15years with the owners consent no rent paid, he has developed the farm over these years, the owner has recently passed away with no will in place, can he hold the property through squatters rights

"with the owners consent" means no. Consent is fatal to a squatter's title

do you know what happens in this situation

The intestacy rules set out in the Succession Act apply. Effectively, the closest living relatives share the estate equally.

the farmer on the farm is a brother of the deceased, does that make a difference even though there are other living relatives

Some detailed info on adverse possession. (not for the faint of heart)

The consent issue is fatal to this situation, so the Succession Act 1965 covers what happens if there is no will, and the closest relatives living inherit - it runs - spouse/children, parents, brothers/sisters, further relatives.

In the situation you describe, if the farmer is a brother, and there are no other brothers and sisters, he inherits it all. If there are others, he gets an equal share with the others.