Complex sentence: Glover used this to blackmail the Richmond Corporation, offering it to them for £4,000 but although the Corporation wanted to buy the island, it was felt that there was no justification in spending such a large sum of money out of its funds.
Split into simpler sentences: Glover used this to blackmail the Richmond Corporation, offering it to them for £4,000. Although the Corporation wanted to buy the island, it was felt that there was no justification in spending such a large sum of money out of its funds.