£25 may be what they'd like you to believe is the going rate, but it's a long way off. The NUJ suggested rate for a year's use for an image of the (approx.) size used is £325 for editorial use and £425 for advertorial and newspaper use. Their use looks like the latter to me, so the minimum they should be paying is £425 for the first year of use. Ongoing use should be negotiated based on expected duration with the license for use renewed periodically if it's expected to be perpetual usage (
or you can negotiate a one time fee if you preferred).
There's a lot of newspaper acquiring images this way, and claiming they didn't know who owned them (the Mail is a major abuser). This doesn't permit them to use those images though and they know that, so the use is wilful.