A second hand 424 will cost you same or less as a Sire. both are excellent so, tough choice. Given a P7 is around the £500 price point, I'll guess that is your budget? If so, be worth looking at this: https://www.ebay.co.uk/itm/284609367748?hash=item42440a4ec4:g:Q4YAAOSwmuZh4dra