Changed the fuel filter today… I thought it would be worth mentioning that the issue isn’t really if the retaining clips should be re-used or not (well the answer is that it isn’t too difficult to remove the old ones intact, but it still makes sense to use new ones…), but more importantly that care should be taken to avoid damaging the right-angle plastic connector on the flexible fuel pipes. The connector can be damaged if prised off the filter using a screwdriver, and as the fuel pipes are under pressure it does not seem like a good idea to replace just the connector bit if it does get damaged… which could mean a fairly complicated procedure if the entire front section of the fuel pipe from the filter to the engine needs replacing.
On another note, I found that rather than fitting the clip on the filter first, and then pushing the right-angle connector on top of the clip, you could actually fit the clip into the right-angle connector first, and then slide the whole thing onto the fuel filter. On one side this was the only way I could get it on, as it wouldn’t ‘click’ in place if the clip was fitted on the filter first. Just a bit of information that hopefully may be helpful to someone one day…