What is the significance of aluminium cobbles

[djprescott]

Recently, whilst visiting Lancashire, I noticed an old cobbled yard in an old industrial area, I think it was where Leyland Trucks were manufactured. Amongst all the cobbles there was an aluminium one.
There must be a reason for this.
Anyone know what it is?

[dot.haukes]

was it not at the leyland Truck museum in Leyland?

[spudqueen]

A couple of weeks ago I walked through the Mersey Tunnel (Birkenhead) for its 75th anniversary and found out that when it was first opened the roadway was made of metal so that it wouldn't wear out. Apparently it didn't last long as cars were slipping all over the place. Possibly this was something along those lines?

[sigma]

They are usually boundary markers for property

[djprescott]

Thanks for the answers.
It wasn't Blackpool Rd Preston. It was in Leyland, where the trucks were originally built, I believe. The site is still there but split into smaller units for businesses. I did wonder if it was some sort of property boundary marker.
Dave.