Thanks for your reply, and apologies for the delay in replying.
If they hold the property as Joint tenants, th eproperty will pass automatically to your brother if you mother dies first.
If they hold it as Tenants in common, your mother's share will be split equally between her children if she did not leave a Will. If your mother does leave a Will, her share will pass to whoever she has nominated in her Will.
I hope this clarifies matters.
Can I be of any more assistance to you?