Well I bought these Dick Meldonian Lps in the middle of the 1980swhen strongly collecting big bands only. Its plain swing oriented big band sound.
The sound is a bit flat due to the life recording and could use some more volume.
Can't say what the speciality of Marion Evans is compared to othe big band arrangers. The charts seem to be normal mainstream swing. The other one I have with that band plays Gene Roland music and these sound very modern.