I think I overheard someone explaining that one at work today; it's the term for some piece of 'assistance' rendered by management to employees that is supposed to save time and money but is actually practically useless. E.g. "I wanted a sword and he gave me a velvet scabbard." The velvet bit refers, I think, to the fact that management find these things quite attractive in a "buzzwords and warm glows" way.

I've got one for you: Pudding elbow

Embarrassment caused by over-reaching oneself. Derived from the fate of those who, in reaching for the cream, dangle their sleeves in the Charlotte Russe.

Cornish Date?

This is a thing rather like a haggis, but instead of wholesome meat and vegetables it's filled with dried fruit. It was originally made for tin miners to take to work as a kind of packed lunch, the rationale being that it was so revolting it would make working in a tin mine seem not so bad after all.

An acquaintance asked if I want to try salty surfing. Do I need a licence?

This is simply another name for bodysurfing, where you use yourself as the board. More salt in the face, you see.

What do you think of a round of foot crepes?

No thanks. Those large, round discs of dead skin from the soles of your feet are hard to make palatable.

Purple lampoon?

As I see it, it's a guy sharking after hours in Cleveland.

I've heard this one but not sure of its meaning: A frayed rope in the pulley.

It's applied to chaps who (ahem) can't get IT up. IT, or Information Technology, is quite a complex undertaking and a broken wire (frayed rope) in the circuit (the pulley) will just prevent the user getting it working (up).

Safari Beard

The results of a night in the bush.

Ahem.

I've heard of a Toilet Duck, but what is a Pantry Chicken?

Ah the Pantry Chicken is that strange little beast that lurks in the larder, but whose existence it is impossible to prove. It is responsible for mysterious crumbs where there used to be cakes. For scuffling, scuttling noises heard on opening the door suddenly. For any strange noises heard through the closed door. And most notably for the fact that eggs - that turn out to be hopelessly addled - turn up in the most unlikely places.
The chicken itself of course is mythical, but it is used to explain any of the above (and many other) inexplicable phenomena involving this store room.

I once overheard an elderly pair of ladies discussing Pimlico pasties - any ideas ?

It's difficult to tell the context from your question, but if the ladies seemed to be the kind of elderly ladies who enjoy their food, then they were probably referring to savoury filled pastry snacks. Pimlico pasties, in particular, are characterised by a generous admixture of horsemeat (Pimlico being a racecourse in Maryland, USA). On the other hand, if the ladies still looked in fine fettle, slim and a little cheeky, they may have been referring to that variation on the glittery stick-on pastie used by strip artistes as a rather vestigial modesty aid - a tip of the hat, if you like, to covering at least one goose pimple - the Pimlico Pastie, made entirely of cellophane.

Stiff Gallop?

I think you misspelt it. A Stiff Gallup is a election/poll/whatever in which all of the choices are equal given the margin of error. So named because it was said that deadlocked votes were the only means of excitement for Mr Gallup.

Tuna Harbour