From a late-war listing of grenades, long after the pitcher had been consigned to history, the Nos 13 and 14 are described thus:
Grenade, hand, No.13 Mark I |L| - This grenade consists of a cylindrical and segmented steel body with shrunk-on base, and enclosing a tin cylinder containing the bursting charge of ammonal, the space between the two cylinders being packed with pitch or lead wool.
Grenade, hand, No.14 Mark I |L| - This grenade consists of a segmented malleable cast-iron body, with an inner tin cylinder containing the bursting charge of ammonal, the space between the two cylinders being packed with pitch.
It puts a question mark over whether any pitcher grenade with a single piece body is a No.13, as the above description is of a two-piece - as per attached drawing. The only contract documentation referring to separate light and heavy pitchers is for the first War Office contracts for 10,000 of each from Roburite and Ammonal Ltd and Decimals Ltd respectively, in April 1915. From July all Ministry contracts simply refer to pitchers, without differentiation as to their being light or heavy.
The implication is that any surviving single piece pitcher is a No.14, whatever its weight; the empty weights seem to come in at around 1lb 1oz, give or take.
The pitcher with original service markings shown below weighs 1lb, 1 1/2oz. Also shown is a brass shell, which is likely a pattern maker's model, made prior to committing to casting in iron.