A group calling itself New Fathers 4 Justice is staging a protest at the top of Carfax Tower in the centre of Oxford.
Two men - dressed as a jester and the Incredible Hulk - climbed to the top of the tower this morning and unfurled banners.
Roger Crawford, 60, from Bedfordshire, and Peter Smith, 33, from Bristol, have been given a 5pm deadline by police to come down.
The men said they represented a splinter organisation from the orginal Fathers 4 Justice campaign group.
They are calling for a review of court procedures involving access to their children.
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