Verona double oven ( about 3 years old ) gas cooker. One of the five burners has stopped working? If I turn the relevant front switch, one hears the usual spark clicking sound and the burner lights up. The burner will stay lit the entire time the switch is pressed. However on release of the switch, the gas flame goes out. I assume a problem with the switch, how can I check this?

Thanking you in anticipation.

Try cleaning the burner according to instructions: http://veronaappliances.com/sites/default/files/vefsgg244-manual.pdf
The probe is most likely dirty and cannot prove the flame.