Sounded like a small end rattling .

[Steptoe]

Engine has 114K miles and had started to get a high pitched tapping noise.
Suspected a little end.

Turned out a far cheaper and easier fix.
It's been a funny old two weeks with lots of unusual problems turning up. .

 

[g00ner]

Whatsthatthen?

 

[Kenny Rodkiss]

Looks like a buggered pushrod.

 

[timeandtide]

Whatsthatthen?

Just what I was thinking!

 

[MattW]

Single cam pushrod.
Had the same thing happen on my 1100 - plus ca change...