The section from Potters Bar to the Dartford Tunnel was constructed in stages from June 1979 onwards , with the final section between Waltham Cross ( Junction 25 ) to Theydon Garnon ( Junction 27 ) opening in January 1984 .
DET NOUN ADP PROPN PROPN ADP DET PROPN PROPN AUX VERB ADP NOUN ADP PROPN NUM ADV , ADP DET ADJ NOUN ADP PROPN PROPN ( NOUN NUM ) ADP PROPN PROPN ( NOUN NUM ) NOUN ADP PROPN NUM .