The battalion was engaged in an attack at Arras, and specifically near a place called the chemical factory

 

 

 

this is the relevant paragraph from the Official History of the 1/7th Bn. Black Watch (TF) war diary for the period of April 22-25 1917

" The 153rd Bgde( Br-Gen D.Campbell) attacked with the 1/7th Black watch on the right and 1/7th

Gordons on the left. Only on the left was the first objective reached behind the barrage but troops were seen going on across the Gavrelle road, and it was only when the reserve battalions , 1/6th Gordons (152 Bgde) and the 1/6th Bw moved up preparatory to the attack on the final objective that the true situation was discovered. Another tank of C Batt. gave the infantry useful aid though it was riddled by armour piercing bullets just north of the railway. After desperate fighting the whole of the first objective was captured, and then the station buildings. .......

An earlier paragraph sets the scene for this attack.

The 51st Div ( Harper) had a peculiarly difficult task owing to the conglomeration of buildings in its path. The straggling village of Roeux, the chateau, the Chemical Works, the station and another group north of the railway, which had already given grim proof of their capacity for resistance.
The 153rd Bgde were relieved that night

 

Also this comes from a set of the History of the Black Watch in the Great War, which goes into a fair bit of detail.

The battalion had taken part in the action at Arras on the 9th of April, it held part of the line until the 18th, when it was relieved. It was brought back up to the front for an attack on the 23rd.

Zero hour was at 4.45am.

Their attack was near to Roeux and the chemical Works.

It was daylight when the attack began and they came under heavy fire from German MG's on Greenland Hill and the Chemical Works.

They had to take cover and the attack was held up. The Officers tried to get the men to rush through gaps in the wire, but the german MG Gunners had these gaps covered. They had taken many casualties and lost a number of officers.

The attack got going again around 9am when a tank appeared on the scene.

They took some of the buildings at the chemical works and also a number of prisoners. Here they were heavily counter attacked, but these mass attacks were broken up by Artillery and MG fire. The history describes the days fighting as ''confused''. The Bn. lost 7 Officers Killed, 5 wounded. 64 O/R Killed 194 wounded and 65 missing.
They held this line until the 24th when the 27th Northumberland Fusiliers relieved them

 

Most of the soldiers killed in this action are buried at Brown's Copse Cemetery, Roeux.

 

25 Apr 1917
Leighton, John Pte
CWGC has him as killed April 22-25, 1917 with no determined date of death.
The Black Watch history of the Great War has battalion rolls of honour in it and has him listed under this date.
Here is his entry from the Scottish National War memorial-

 

 

 

Surname	LEIGHTON
Firstname	John
Service Number	292919
Date Death	25/04/1917
Decoration
Place of birth	Dundee
Other	7th Bn.
SNWM roll	THE BLACK WATCH (ROYAL HIGHLANDERS)
Rank	Pte
Theatre of death	F.& F.