Good news is that this particular MGF lives once again.
Retraced a few steps on the back of great advice from Cobber - fuel pressure/flow rate test which threw up a few issues. Replaced the fuel filter as advised (despite fuel filter being new) - and started first time - go figure.
Pulls as it should, idles at right speed, seems a little lumpy when pulling away in 1st at junctions after running for 10-15 mins, but maybe just needs some miles in it.