All done now. The mobile mechanic had to smash it off in the end. For reason it had been super glued on.
While doing my spark plugs though, after taking out my 3rd one, lots of oil spurted out, so need to fix that, but only costing me £75 for him to come back to do it.
Also one other question. He said he could do a engine flush for £10. But I have heard that sometimes doing a engine flush on a old car, although in the short term you get better performance, sometimes as it has been all flushed out, you may get some problems with the engine that have been hid away with all the gunk.
So would it be worth doing one?