Can anyone help date this bike?

Shaun, definitely not the man to sit behind in a break.
He was in the 10 man hercules team that rode the T de F 1955. I think I saw him in one of the recently offered recordings here. Two of the team finished, Dave lasted 4 or 5 days from memory. The following year I rode an early road race containing most of the 1955 team and didn't see further than the hub in front of me for the first 55 miles, which we covered in (for us a bit fast) 2 hours.

Keith,
You suggest the forks could be a replacement, interesting thought, but I'm fairly certain they were the same colour and type of paint as the frame, a sort of metalic light blue.

Do you know if head badge designs were registered like trademarks? If so where do they get registered, because I have found other evidence to suggest in 1951 they were using the Micrometer D rather than the crossed swords

Chris

Chris, The front fork blades look like D to round, as used on roadster bikes. I have never seen butted 531 in that shape, but it might have existed.
There is some confusion about dayton Elite and Roadmaster, but the company only made bikes till 1955. Amalgam refers to their electric welded frames with 1" tubes. The names might be interchangable.
Probably towards the end they would have made frames from anything they could get.
No connection with Dayton in the US.

For me "collectible", "rare" and "class frame" are rarely synonymous.
My speciality is the Thanet "Silverlight" which is a total heap of rubbish, but a frame will fetch £1500.

An update

Thanks to all of you for the feedback,
I have done various further bits of digging on the internet, and based on that;
The headbadge OldTel thought the micrometer design was pre-war,however I have found via http://sports.groups.yahoo.com/group/Bi ... ssage/6368 a similar headbadge on a Dayton of the 1940s, and the Dayton catalogue of 1954 and other restorations of bikes of the 50s show the micrometer design
OldTel suggests the spur on the dropouts suggests the 40s
OldTel also supplied the page from the 1948 catalogue which KeithGlos thought showed a 51 model, but having seen the full catalogue the page before (see attachment) does say the lugged version was for 26" wheels (not 27" as the amalgam frame) and was built from double butted 531.

These to me suggest it is genuine and probably pre 1950, my research into trademarks hasn't helped date the headbadge. However there was a seattube decal and the trademark search shows that in 1942 Dayton registered a logo with the micrometer D design with the word cycles beneath it, but in 1947 they registered an almost identical one with the word Dayton replacing cycles, however on the 1948 catalogue they used the older design on the cover
Next task look through very old photos to see if I took any pre repaint pictures