I posted a brief excerpt about the original Syon Abbey from the Syon Park website on May 4.
The history goes on to explain what happened after the dissolution of the Abbey in 1539:
After the suppression of the abbey, the estate became Crown property and became the possession of the 1st Duke of Somerset, the Lord Protector to the young son of King Henry VIII, Edward VI. He built Syon House in the Italian Renaissance style, over the foundations of the west end of the huge abbey church, (which was the size of a cathedral), between 1547 and his death by execution in 1552. Syon was then acquired by a rival, John Dudley, Duke of Northumberland (no relation to the present family.) The Duke's son, Lord Guildford Dudley, had married Lady Jane Grey, the great-granddaughter of King Henry VII and it was at Syon that she was formally offered the Crown by the Duke. She accepted reluctantly, was conveyed to London by river and proclaimed Queen. Nine days later, she was displaced by King Henry VIII's eldest daughter, Mary Tudor. The following year Lady Jane Grey was executed. In 1557, the Roman Catholic Queen Mary recalled the nuns to re-establish their abbey at Syon. But she died suddenly in 1558 and the nuns left the country on the accession of her Protestant sister, Queen Elizabeth I. (In 1861 the nuns returned to England to found their religious community in Devon, where they reside to this day). In 1594, Henry Percy, 9th Earl of Northumberland, acquired Syon through his marriage to Dorothy Devereux and the Percy family has lived at Syon House ever since.
The history page also includes this link to a description of excavations and information about the "Lost Abbey of Sion".
One event the history omits is that Catherine Howard was kept sequestered in the former abbey while Henry VIII and his courtiers investigated the charges of treason against her. Then she was moved to the Tower of London when Parliament passed a Bill of Attainder against her, in preparation for her execution.