Tony....sorry for delay in reply....been asking questions.
My father born 1920's doesn't recall Heath Road being called Cross Road and neither does my uncle who lived in Lexden for about 70 years.
I lived on Straight Road for 12 years....(60's mainly)
On the old maps, even when the Heath was still there, it appears to be Heath Road.
Funnily enough, neither of the two junctions we are talking about are really (even at a push) crossroads.....the nearest to a crossroad is Hetah Road / Claremont Road/Avenue....even that is staggered.
Myself, my father and uncle, plus a couple of my mates can recall there being a 'garage' of a sort, on the Murco site, before Murco......it consisted of a couple of pumps and a white painted weatherboarded shed (garden shed size).....it may have been Tweeds, we don't know.
Is it really a 1912 planning application?.....sure it isn't 'by-laws'?......Does 1912 fit with your g-grandfather's age?.....surely you ain't that much youger than me, unless you moved away fairly quickly after being born our paths have probably crossed.
The garage on the corner of Straight Road certainly wasn't really a 'showroom'.....if you want to call it that.....although it had some large windows onto London Road, the premises were, to the best of our recollection. a combination of sheds in weatherboard, painted in a dirty or blackish green.....the floors were earth.
Absolutely certain it went right up to the Nelson Road boundary.
My father and I think it was Tweeds, my uncle says he thinks it was also, but two others aren't certain.....the trouble is, the Tweeds appeared to have a lot of fingers in lots of pies in the area.....If I can track down my old schoolmate Andrew Tweed, I will ask him (he should still be in Colchester).
I'll keep digging ( I have found a few postcard photos of Lexden on a website, but I won't post them here.....you have probably already found them).
Al.