Callajoppa cirrogaster is very similar to Callajoppa exaltatoria. They are two of the largest Ichneumonidae in Britain but can be hard to tell apart. Both are similar in coloration and have pale markings at the base of the antennae as well as yellow colouration around the eyes and at the base of the abdomen. The wings of both species are distinctly yellow, which gradually darkens to brown at the edges. (see link below for further detail).

Callajoppa exaltatoria

Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed.

Mainly in woodland and parks where large hawk-moths are found.

July to September.

A parasitoid of hawk-moths.

Status in Britain is difficult to determine due to lack of records.

Status in Leicestershire and Rutland not known.

https://www.nhm.ac.uk/content/dam/nhmwww/take-part/identify-nature/british-ichneumonid-wasps-id-guide.pdf