I don't think it's supposed to represent either. It's just a railway-ish pictogram that is in the style of the letter "M" for Manchester. See the images below.
I thought these were commissioned by Railtrack, but they must have been later as Reading and Liverpool Lime Street weren't classed as Major Stations when privatisation happened.
And incidentally, these are a classic demonstration of why silly branding of railway stations with coloured logos and the like is to be discouraged. Half of these logos don't mean anything or make any sense whatsoever.
We, for example, probably know that the Euston sign represents the Doric Arch. I'd be very surprised if anybody who isn't a member of this forum knows that though!. Likewise, what's the Reading symbol supposed to be? Or Birmingham New Street? What do the different colours represent? Why does Cannon Sreet not have the letter 'C' in it, or Victoria the letter 'V' (unless you take the lapel of the dress to be a 'V')? Why is the 'L' in Leeds obscured by the Yorkshire Rose, and why are all the 'L's in the symbols for Leeds, Liverpool, Liverpool Street, and London Bridge all different sizes, etc.?
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