I would have said almost certainly a buzzard. The wings do not look long enough for an eagle. The main ways of distinguishing between buzzards and eagles are their size which can be difficult to tell if they are high in the sky and location. Mountains ( you tend not to see buzzards in the heart of the northern Cairngorms) - more likely an eagle. Glens and farmland - more likely a buzzard.
Common birds of prey in flight: 1: Kestrel hovering - only kestrels hover for any length of time; 2: Kestrel gliding - note slender, pointed wings, long tail and slender body; 3: Peregrine - note heavier body, stouter wings and slightly shorter tail than kestrel; 4: Buzzard - large bird with short rounded tail and broad wings, usually with 'fingers' of primary feathers; 5: Sparrowhawk - much smaller than buzzard with short, rounded wings and conspicuously long tail.