Just to close this off, the Dell switch wouldn't negotiate with the SP kit (not sure what it is. There is Juniper somewhere doing VRRP). Changed to hard set speed/duplex and it started working. Bit concerning that negotiation failed.
Hi, Switch: Dell S5224-ONEnvironment: Data CentreFibre: multiple 1Gb SMF links (1 metro connect; 2x Internet breakout) Unable to get links working - auto negotiation is being used by the provider. A DC tech came round with their tester and verified the signal from the DC. They then connected to the switch SFP module and there was no signal when using the recommended "negotiation auto" setting. When I turned "negotiation off" there was signal but we couldn't pass traffic (couldn't ping IPs on the same subnet and couldn't see any arp entries). You can see the output below  
S5000 SFP with SMF - protocol down