Complex sentence: It is one of the tallest structures in the United Kingdom, the tallest being the mast at Belmont with a height of, however at above sea level, Winter Hill has the highest television transmitting antenna in the UK.
Split into simpler sentences: It is one of the tallest structures in the United Kingdom, the tallest being the mast at Belmont with a height of. At above sea level, Winter Hill has the highest television transmitting antenna in the UK.