About 3.5 - 4cm long. Feeding on ribwort plantain.
No interactions present.
Was it really as big as 3.5-4cm? It is a very good match for the 15mm ruby tiger in ukleps but at 3-4 cm a Ruby Tiger couldnt look like the above larva, nor a Muslin Moth as it would be quite mature and brown.
May be an over estimate but 1.5cm seem rather small. This image is cropped down from the original which was taken at 1:1 so I can work it out. Will post a more accurate length tonight.
Lat/Lng: 52.725425502573, 0.30971199274063
OS grid ref: TF560166
Sown wildflower meadow about 10 years old