A recording of a Green Warbler by Stuart Fisher in Kumarakom, India is available here and one of a Two-barred Greenish by James Eaton at Mondulkiri in Cambodia here. Note the lack of House Sparrow like "chirrup" quality to the Greenish Warbler, present in both Two-barred and Green. The Church Cove bird also lacks this.
The top sonogram was kindly created by Hugh Harrop is a high temporal resolution version of two of the clearer calls. The bottom version, created by Neil Hagley is a longer version of the recording. Both are a near-perfect match of the Greenish Warbler sonograms published in the 2001 Dutch birding article by van der Vliet et al, available here (if you subscribe to RBA - you can also get it with the 7 day free trial), Green has a W-shaped sonogram and Two-barred even more peaks and troughs. There are a whole bunch of useful songs and sonograms here.
Incidentally - there are some more photos of the bird here. The third one down initially struck me as particularly interesting as it does suggest that the bird had a more typical Green Warbler wing formula - i.e. P3 and P4 are the longest and P2 is between P6 and P7 in length. In Greenish P4 and P5 are generally (although not always) the longest and in only 14% of females and 9% of males is P2=P6-7 (see Dutch Birding article here). However, there are some more photos in the UK400Club blog here. On this photo, the wing formula is suggestive of Greenish - i.e. P4 & 5 look the longest and p2=P7-8. This demonstrates the hazard of determing wing formulae from photographs.