I guess you live in Wales and your brother-in-law lives over the border.
Before 1998, the rule on elections for chair was as you describe throughout England and Wales. The 1998 Education Act gave governing bodies the freedom to elect a chair for between one and four years, but the WelshAssembly opted to keep the annual election. I personally think it is wiser to have annual elections. If a governing body has elected a chair for four years and is disappointed with his or her performance, there is nothing they can do about it. While no one wants change for change's sake, an annual election is a simple and kind way of doing it, if necessary, giving another governor a chance and perhaps reinvigorating a tired governing body.
You should feel reassured that your governing body retains confidence in you, but seven years is quite a long time and you might consider sounding out your colleagues on whether they would like a change, and, if so, stand down voluntarily. They might welcome this and be grateful to you for making it easy. You ought perhaps also to consider your vice-chair's position. He or she may feel ready to take over: remember, "Hope long deferred maketh the heart sick".
The change in 1998 was very much in keeping with others made at the same time, reflecting the belief that a business-like governing body was more important than an open and democratic one. I think the Welsh chose wisely.
Questions for Joan Sallis should be sent to The TES, Admiral House, 66-68