.cpt is a Corel PHOTO-PAINT bitmap file, so yes TIFF would have been a likely format then.

However, your files are .cph type, which are not bitmaps, so renaming them to .tif will have no effect.

If you drop them into a text editor you can read stuff like:

Cream of Tomato and Rice Soup
with Bread Roll & Butter

Homecooked Leg of Lamb
Carved onto a bed of peaches
Homecooked Whole Turkey Carved by our Chef’s
Homecooked Whole Sirloin of Beef Carved by our chefs
Whole Poached Salmon with Prawns Carved by our Chefs
Mixed Leaf Salad with Olive Dressing
Tomato and Red Onion Salad with Cucumber Ribbons
Braised Red Cabbage with Orange & Herbs
Half Eggs with Prawns Mayonnaise
Sweet Potato Salad with Irish Scallions
Beetroot Salad with Vinagarette

Basket of Hot Crusty Rolls with Butter

Strawberry & Orange Sorbret & Grand Marnier Cream
and

Homecooked Ham with Peaches
Homecooked Topside of Beef with York Batter
Homecooked Chicken Jeanettes with Wine Sauce
Poached Salmon with Prawns & Marie-Rose Sauce
Mixed Leaf Salad with Olive Dressing
Braised Savoy Cabbage & Bacon Salad
Apple, Celery and Walnut Salad
Long Grain Rice Salad with Peppers
Maccaroni Pasta & Blue Cheese Dressing
Hot Buttered Jacket Potatoes with Chives

Basket of Hot Crusty Bread Rolls & Butter

Warm Chocolate Fudge Cake with Cream & Ice Cream