B777 CREW HAD TXWY INCURSION AT EGTT.

Narrative

AFTER ARR IN LHR (B777) GATE WAS OCCUPIED. GND TAXIED US TO A VERY UNUSUAL HOLD AREA AND HELD UNTIL OUR GATE WAS AVAILABLE. A B747-400 WAS TAXIED IN FRONT OF US TO CROSS RWY 27L AND GND CLRED US TO THE GATE VIA THE INNER TXWY. HOWEVER THE GATE IS NOT TO BE USED BY B777 AND B747 DUE TO LACK OF WINGTIP CLRNC (BUT THESE ACFT UNDER TOW IS OKAY)? I GLANCED AT MY GATE TAXI CHART BUT IT DID NOT SHOW THIS RESTR ON THAT MAY LIKE ON THE 10-9 TAXI CHART. I GLANCED AHEAD OF THE ACFT AND IT LOOKED LIKE IT WOULD 'FIT.' MY OVERZEALOUS CONFIDENCE HAVING BEEN TO LHR SO OFTEN I ADVISED THE CAPT WE COULD TAXI HERE. I WAS QUESTIONING MYSELF A LITTLE...THE GND CTLR TOLD US TO 'STOP.' AN OPS VEHICLE WAS CALLED OUT TO LOOK AT THE PROB AND HE LED US OUT OF THERE IN SECONDS. (PERSONALLY IT DID NOT APPEAR TO BE CLOSE AT ALL TO ME; HOWEVER IT IS IN A TURN AT GATE AREA AND SAFETY MARGINS MAY BE REDUCED.) MY ARROGANCE WAS AT FAULT. THE GATE CHART HAD THE TXWYS BUT NOT RESTRS. THE B747 TAXIING IN FRONT OF US LED US TO BELIEVE WE SHOULD TAXI NOW ON THE INNER. NO BENT METAL; NO STRESSED CONCRETE; NO DELAYS; JUST A BLOW TO THE OLD EGO.