inserts in the black leather effect vinyl. The development of the convertible version of the TR7 required the interior light, which was in the headlining, to be removed. This was replaced by lights with integral switches in each of the door cards. A map light, mounted between the seats on the back panel below the rear parcel shelf, was deleted. The convertible also required a smaller fuel filler cap, as the deck area in front of the boot lid was reduced to allow for the stowage of the hood. These modifications were also applied to the hard top for the 1978 year model (starting after the factory's summer shutdown in 1977), presumably to maintain commonality of parts on the assembly line. The wheel trims were also changed at this time, from smaller black trims that covered only the centre of the wheels, to larger silver ones, covering the whole wheel. External decor changes included simplification of the TR7 badge on the boot, the rear panel changing from black to body-colour, and the TR7 nose badge being replaced by a large laurel-wreath emblem with the Triumph name across its centre, this latter replaced on final production models by a small circular raised badge. Only a small number of 1978 year model cars, with the smaller filler cap and lights in the door cards, were produced at Speke, due to the industrial action there in 1977–78. The development of a V8-engined version, which became the Triumph TR8, required an addition bulge in the bonnet, to clear the carburettors. This produced the "double bulge" or "double bump" bonnet, characteristic of TR7s and TR8s built at Canley and Solihull. However, at least some of the TR7s built at Canley have single bump bonnets; though it is possible these were cars that had not been completed at Speke, possibly due to the industrial action there, and finished off at Canley after production was moved. During production at Canley, the seat trim was again revised, with a plaid cloth in navy blue or tan, with matching coloured leather effect edging, and matching door cards. A further trim change during production at Solihull saw the use of a ruched velour in blue or tan on the seats, with matching inserts on the doors. Also, the internal door lock buttons were changed from the earlier standard BL round ones, to rectangular buttons held on with small grub screws.