SHOP workers believe they were just moments from ‘catastrophe’ after a huge gas leak underneath their store.

An anonymous early-morning passer-by raised the alarm after smelling gas outside Wynsors World of Shoes, in Accrington Road, Blackburn.

Staff turned up at 8am to open up but, instead, found engineers from National Grid waiting to get inside.

Workers said they were told a light switch could have ignited the gas – and were then forced to close for four days while the problem was fixed.

Shop supervisor Adele Matthews said: “The engineers wouldn’t let us in, except our manager who had to open up for them.

“Then we only got back in three days later and could only open to the public the day after that.

“We couldn’t smell anything the night before, but we all went home feeling a bit groggy.

“Then, on the morning we turned up, it absolutely stank.”

Mrs Matthews said all the staff wanted to say ‘thank you’ to the unknown passer-by.

She added: “We all smelt the gas, but we might still have gone in and opened up the shop.

“If we had done that, it would have been an absolute catastrophe.

“One of the engineers showed me the readings and said if we had switched on the power, it would have been explosive.”

The store was closed to the public for four days before reopening last Saturday.

Mrs Matthews said she could not estimate how much trade was lost, but said it would have been ‘many thousands’.

A National Grid spokeswoman said a cracked pipe underneath the Wynsors store had caused the alarm.

Gas had permeated through concrete and into the shop and surr-ounding area, she said.